Wave Interaction with Defects in Pressurised Composite Structures

Abstract

There exists a great variety of structural failure modes which must be frequently inspected to ensure continuous structural integrity of composite structures. This work presents a finite element (FE) based method for calculating wave interaction with damage within structures of arbitrary layering and geometric complexity. The principal novelty is the investigation of pre-stress effect on wave propagation and scattering in layered structures. A wave finite element (WFE) method, which combines FE analysis with periodic structure theory (PST), is used to predict the wave propagation properties along periodic waveguides of the structural system. This is then coupled to the full FE model of a coupling joint within which structural damage is modelled, in order to quantify wave interaction coefficients through the joint. Pre-stress impact is quantified by comparison of results under pressurised and non-pressurised scenarios. The results show that including these pressurisation effects in calculations is essential. This is of specific relevance to aircraft structures being intensely pressurised while on air. Numerical case studies are exhibited for different forms of damage type. The exhibited results are validated against available analytical and experimental results.

Bayesian inference for damage identification based on analytical probabilistic model of scattering coefficient estimators and ultrafast wave scattering simulation scheme

“…This relies on post-processing a standard FE model of a small segment of each waveguide using periodic structure theory. The degrees of freedom (DoF) at the interfaces of the WFE and FE models of the waveguides and the damage are compatible in order to avoid requirement for further computational treatment [47,48]. The models are coupled to yield the reflection and transmission matrices of the damage.…”

Bayesian Damage Characterization Based on Probabilistic Model of Scattering Coefficients and Hybrid Wave Finite Element Model Scheme

“…A common choice for the training design is the Latin Hypercube Design (LHD), which guarantees to spread design points evenly across each input parameter dimension. With the training set at hand, one can then calculate the predicted values of the surrogate model at various sample points in the parameter space by performing an "experiment" at each of those samples based on the hybrid WFE scheme [14][15][16].…”

Development of a Multi Degree-of-Freedom Vibration Exciter for Laboratory Applications

“…The strength of aluminum A356 alloy was enhanced using ultrasonic vibration during the production of its castings [Jianbo et al, 2009]. Vibration has also been applied to other manufacturing processes such as burnishing of aluminum [Travieso et al, 2015], welding of stainless steel [Sakthivel and Sivakumar, 2014], laser powder deposition on alloy steel [Eshan et al, 2009] characterization of composite structure [Apalowo and Chronopoulos, 2018] and sieving of agricultural grains.…”