Prediction of attenuated guided waves propagation in carbon fiber composites using Rayleigh damping model (original) (raw)
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Prediction of attenuated guided wave propagation in carbon fiber composites
Attenuation of Lamb waves, both fundamental symmetric and anti-symmetric modes, propagating through carbon fiber reinforced polymer (CFRP) was modeled using the multi-physics finite element methods (MP-FEM) and compared with experimental results. Composite plates typical of aerospace applications were used and provide actuation using integrated piezoelectric wafer active sensor (PWAS) transducers. The MP-FEM implementation was used to combine electro active sensing materials and structural composite materials. Simulation results obtained with appropriate level of Rayleigh damping are correlated with experimental measurements. Relation between viscous damping and Rayleigh damping are presented and the effects on wave attenuation due to material damping and geometry spreading are discussed. The Rayleigh damping model was used to compute the wave damping coefficient at several frequencies for S0 and A0 modes. The challenge of multi-modal guided Lamb wave propagation is discussed.
Guided wave propagation in carbon composite laminate using piezoelectric wafer active sensors
Health Monitoring of Structural and Biological Systems 2013, 2013
Attenuation of Lamb waves, both fundamental symmetric and anti-symmetric modes, propagating through carbon fiber reinforced polymer (CFRP) was modeled using the multi-physics finite element methods (MP-FEM) and compared with experimental results. Composite plates typical of aerospace applications were used and provide actuation using integrated piezoelectric wafer active sensors (PWAS) transducer. The MP-FEM implementation was used to combine electro active sensing materials and structural composite materials. Simulation results obtained with appropriate level of Rayleigh damping are correlated with experimental measurements. Relation between viscous damping and Rayleigh damping were presented and a discussion about wave attenuation due to material damping and geometry spreading have been led. The Rayleigh damping model was used to compute the wave damping coefficient for several frequency and for S0 and A0 mode. The challenge has been examined and discussed when the guided Lamb wave propagation is multimodal.
Guided wave propagation in composite laminates using piezoelectric wafer active sensors
Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive transducers that enable a large class of structural health monitoring (SHM) applications such as: (a) embedded guided wave ultrasonics, i.e., pitch-catch, pulse-echo, phased arrays; (b) high-frequency modal sensing, i.e., electro-mechanical impedance method; and (c) passive detection. The focus of this paper is on the challenges posed by using PWAS transducers in the composite laminate structures as different from the metallic structures on which this methodology was initially developed. After a brief introduction, the paper reviews the PWAS-based SHM principles. It follows with a discussion of guided wave propagation in composites and PWAS tuning effects. Then, the mechanical effect is discussed on the integration of piezoelectric wafer inside the laminate using a compression after impact. Experiments were performed on a glass fiber laminate, employing PWAS to measure the attenuation coefficient. Finally, the paper presents some experimental and multi-physics finite element method (MP-FEM) results on guided wave propagation in composite laminate specimens.
Electromechanical impedance spectroscopy (EMIS) and guided wave (GUW) propagation are a popular structural health monitoring (SHM) technique, which had found applications in many fields of engineering: mechanical, aerospace, civil and others. Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive transducers that enable a large class of SHM applications such as: (a) embedded GUW ultrasonic, i.e., pitch-catch, pulse-echo, phased arrays; (b) high-frequency modal sensing, i.e., EMIS method; and (c) passive detection, i.e., acoustic emission (AE). The aim of the work presented in this paper is to provide tools to extend modelling capacities and improve quality and reliability of EMIS and 2-D GUW propagation models using commercially available multi-physics finite element method (MP-FEM) packages on fibre reinforces polymers (FRP). The focus of this paper is on the challenges posed by using PWAS transducers in the composite laminate structures as different from the metallic structures on which this methodology was initially developed.
Simulation of wave propagation in damped composite structures with piezoelectric coupling
Journal of Theoretical and Applied Mechanics, 2011
This paper presents an efficient and accurate simulation approach to shorten time and cost of the necessary pre-tests in the design process of structural health monitoring (SHM) systems. The simulation is performed using the time domain spectral element method, which leads to an optimally concentrated mass matrix and results in a crucial reduction of complexity of the time integration algorithm. The theoretical background of the method and a spectral element for flat shells are presented. New approaches to incorporate the anisotropic material damping and an efficient coupling of piezoelectric elements within the spectral element framework are developed. Some numerical calculations are performed showing both the accuracy of this methodology, by comparing to experimental values, and the applicability to more complex structures like stiffened curved panels.
2010
The necessity of the aerospace industry to reduce the cost, but to keep good safety standards has brought to the improvement of Structural Health Monitoring (SHM) applications. The objective of a SHM system is to allow an easily an low-cost detection of damages, before critical levels. As the diffusion of composite materials poses relevant problem regarding damage tolerance and damage detectability, SHM is one of the most promising technique for the development of lighter, more efficient and more reliable structures. Guided waves are one of the most interesting instruments for damage identification, basing on in-situ actuation and acquisition and on the possibility to correlate anomalies in wave propagation with internal damage. Modeling this kind of waves with a versatile approach as the Finite Elements (FE) allows great improvements in the SHM field of research, because this approach can reduce the experimental analyses and thus the development costs of a SHM system. Since the complex nature of the guided waves, especially in composite laminates, a validation of these FE models must be provided. This is the objective of this thesis. To accomplish this task the results obtained by the FE models are compared with the ones provided by another numerical technique expressly developed to model waves in plates. Such a technique is known as Semi-Analytical Finite Element (SAFE). This comparison is only possible after a particular post-processing technique, which involve the recursive use of the Fourier transform, of the displacements measured in the FE models. Finally these data are compared with the ones obtained from an experimental analysis of three different type of laminates. Since the results of the FE, of the SAFE and of the experiments are very similar, it is demonstrated that the FE models provided are well-suited to represent wave propagation in composite plates.
Sustainability
Today, structural health monitoring (SHM) systems based on guided wave (GW) propagation represent an effective methodology for understating the structural integrity of primary and secondary structures, also made of composite materials. However, the sensitivity to damage detection promoted by these systems can be altered by such factors as the geometry of the monitored parts, as well as the environmental and operational conditions (EOCs). Experimental investigations are fundamental but require a long time period and are costly, especially for tests in real-life scenarios. Experimentally validated simulations can help designers to improve SHM effectiveness due to the possibility of further broadening study on the different geometries, load cases, and material types with less effort. From this point of view, this paper presents two finite element (FE) modeling approaches for the simulation of GW propagation in composite panels. The case study consists of a flat and a curved composite p...
2022
The most common researched area of damage in a composite material such as carbon fibre reinforced plastics (CFRP) used currently in aircraft construction is barely visible impact damage (BVID), significantly reducing mechanical properties. Early detection and qualification would improve safety and reduce the cost of repair. In this context, structural health monitoring (SHM) techniques have been developed that could monitor a structure at any time by using a network of sensors. Widely used discrete ceramic transducers can generate and sense Lamb waves travelling in the structure. Wave propagation must then be analysed for effective damage identification. An effective SHM system is desired to meet several demands, such as minimised weight penalty, non-intrusive system not interfering with the structure performance, costeffectiveness for implementation with targeted sensitivity and area coverage, capability of monitoring non-accessible and critical hot spot regions, robustness, and reliability. This review starts with an introduction on Lamb waves fundamentals and their use in SHM, and then particularly focuses on methods using piezoelectric transducers and mode selection. Some relevant applications on different structural configurations are discussed. Finally, recent developments on piezoelectric coating and direct-write sensor technology for tailored transducers are highlighted with some thoughts for near future research work.
2014
Carbon Fiber Reinforced Polymer composites have been developed since the ’60s and allow the design of resistant and innovative lightweight primary structures, replacing traditional metallic materials. However, their intensive structural use remains limited due, between also other factors, to several peculiar damage mechanisms able to quickly degrade the mechanical properties and requiring high maintenance costs due to service interruptions needed for carrying out periodical non-destructive testing inspections. One solution, more and more suggested and proposed in the literature, is then to apply a structural health monitoring approach. The present paper investigates such possibility focusing on the application of the “Design of Experiment” methodology to the performance of Lamb ultrasonic waves-based monitoring carried out using piezoelectric transducers bonded on the surface of aeronautical laminates. The choice of a Design Of Experiment approach is based on the well-known fact tha...