Longitudinal guided waves confined in radius filler regions of composite joints.
15 Jul 2016-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 140, Iss: 1, pp 334-343
TL;DR: Semi-analytical finite element simulations are used to demonstrate the existence of a longitudinal guided ultrasonic mode confined or trapped in the Noodle regions, and reveal that this mode has attractive properties for rapid screening of Noodle joints, including strong energy concentration, low dispersion, and attenuation.
Abstract: This paper studies the feasibility of using ultrasonic guided waves for fast inspection of conformal deltoid radius filler or “Noodle” regions of joints in stringer composite structures. Semi-analytical finite element simulations, supported by experiments and three-dimensional finite element models, are used to demonstrate the existence of a longitudinal guided ultrasonic mode confined or trapped in the Noodle regions. Studies reveal that this mode has attractive properties for rapid screening of Noodle joints, including strong energy concentration, low dispersion, and attenuation. Discussing the physics of mode confinement in light of material differences and geometry, the phenomenon is shown to be related to feature-guiding effects noted in literature recently.
Citations
More filters
01 Jun 2022
TL;DR: In this paper , the feature guided wave (FGW) was used for inspection of RSW nuclear canisters to ensure safe storage and targeted repackaging of nuclear material in a complex environment which frequently has accessibility issues.
Abstract: Resistance Seam Welding (RSW) is frequently used in many industries where low-cost mass manufacturing of gas/fluid-tight seals are required. One particular use case is in the fabrication of canisters to store nuclear material. Given the expected long lifetime and high replacement cost associated with nuclear infrastructure, it is common for an increase in the design life to be sought during operation. This leads to a need to integrate Non-Destructive Testing (NDT) techniques in a complex environment which frequently has accessibility issues. For the inspection of RSW nuclear canisters, one promising solution is to use Feature Guided Waves (FGWs) to rapidly screen the whole circumferential RSW joint from only partial circumferential access to ensure safe storage and targeted repackaging. FGWs can travel long distances while locally confining their energy to a topological feature such as a weld or stiffener. This paper explores such use of FGWs through both theoretical and practical experimental methods. To understand which FGW modes exist in the RSW joint, the Semi-Analytical Finite Element (SAFE) method was used, revealing four suitable wave modes. An anti-symmetric flexural RSW guided mode was down-selected due to its ease of excitation, intense energy concentration around the RSW, low dispersion and attenuation. Three-dimensional Finite Element (FE) simulations were conducted to explore the sensitivity of the flexural FGW to transverse cracks of differing dimensions. Experimental results on simplified and realistic geometries to transverse crack defects of ≥1 mm deep show the efficacy of using this method to efficiently screen nuclear canister RSW joints for such defects in-situ.
2 citations
Patent•
13 Feb 2020
TL;DR: In this article, the structural health of the noodle area of an adhesively bonded curved composite laminate structure is monitored using interface guided waves (IGW) for non-destructive inspection.
Abstract: Systems and methods for non-destructive inspection of curved composite laminate structures using interface guided waves. In particular, if the curved composite laminate structure has a noodle, then the noodle area may be inspected using interface guided waves. The systems and methods provide a repeatable and reliable nondestructive technique for monitoring the structural health of the noodle area of an adhesively bonded curved composite laminate structure by comparing detection data acquired from an inspected curved composite laminate structure with prediction data derived using a simulated curved composite laminate structure.
References
More filters
Book•
01 Sep 2004
TL;DR: In this article, the theory of elasticity was introduced and basic formulas and concepts in complex variables in the theory and application of wave propagation were discussed. But the authors did not consider the effects of wave scattering on the wave propagation experiments.
Abstract: Preface 1. Introduction 2. Dispersion principles 3. Unbounded isotropic and anisotropic media 4. Reflection and refraction 5. Oblique incidence 6. Wave scattering 7. Surface and subsurface waves 8. Waves in plates 9. Interface waves 10. Layer on a half space 11. Waves in rods 12. Waves in hollow cylinders 13. Guided waves in multiple layers 14. Source influence 15. Horizontal shear 16. Waves in an anisotropic layer 17. Elastic constant determination 18. Waves in viscoelastic media 19. Stress influence 20. Boundary element methods Bibliography Appendices A. Ultrasonic nondestructive testing principles, analysis and display technology B. Basic formulas and concepts in the theory of elasticity C. Basic formulas in complex variables D. Schlieren imaging and dynamic photoelasticity E. Key wave propagation experiments Index.
2,570 citations
TL;DR: In this article, the benefits and drawbacks of z-pinning on the interlaminar toughness, damage tolerance and in-plane mechanical properties are compared against other common types of through-thickness reinforcement for composites, such as 3D weaving and stitching.
Abstract: This paper reviews published research into polymer composite laminates reinforced in the through-thickness direction with z-pins. Research into the manufacture, microstructure, delamination resistance, damage tolerance, joint strength and mechanical properties of z-pinned composites is described. Benefits of reinforcing composites with z-pins are assessed, including improvements to the delamination toughness, impact damage resistance, post-impact damage tolerance and through-thickness properties. Improvements to the failure strength of bonded and bearing joints due to z-pinning are also examined. The paper also reviews research into the adverse effects of z-pins on the in-plane mechanical properties, which includes reduced elastic modulus, strength and fatigue performance. Mechanisms responsible for the reduction to the in-plane properties are discussed, and techniques to minimise the adverse effect of z-pins are described. The benefits and drawbacks of z-pinning on the interlaminar toughness, damage tolerance and in-plane mechanical properties are compared against other common types of through-thickness reinforcement for composites, such as 3D weaving and stitching. Gaps in our understanding and unresolved research problems with z-pinned composites are identified to provide a road map for future research into these materials.
630 citations
TL;DR: In this article, the authors address methods to dramatically enhance computational efficiency by only meshing a local region of the material surrounding the defect; this reduction requires some kind of boundary, or boundary condition, which absorbs, rather than reflects, any waves arriving at the exterior of the modeled domain.
Abstract: Finite Element models for simulating wave propagation and scattering from defects are vital for ultrasonic methods in NDE. This article addresses methods to dramatically enhance computational efficiency by only meshing a local region of the material surrounding the defect; this reduction requires some kind of boundary, or boundary condition, which absorbs, rather than reflects, any waves arriving at the exterior of the modelled domain. A variety of approaches exist and we take two approaches, Perfectly Matched Layers (PML) and Absorbing Regions, selected specifically as they are readily implemented in commercially available Finite Element packages without requiring the source code. We illustrate both bulk and guided waves, and analysis is used to guide the performance, and thus to plan the use, of each of them. Finally, application examples illustrate the gains yielded by absorbing layer methods in terms of reducing both model size and unwanted reflections.
163 citations
TL;DR: The paper presents the principles of a procedure and then validates and illustrates its use on some examples, and makes use of absorbing regions of material at the exterior bounds of the discretized domain.
Abstract: The Semi-Analytical Finite Element (SAFE) method is becoming established as a convenient method to calculate the properties of waves which may propagate in a waveguide which has arbitrary cross-sectional shape but which is invariant in the propagation direction. A number of researchers have reported work relating to lossless elastic waves, and recently the solutions for nonpropagating waves in elastic guides and for complex waves in viscoelastic guides have been presented. This paper presents a further development, addressing the problem of attenuating waves in which the attenuation is caused by leakage from the waveguide into a surrounding material. This has broad relevance to many practical problems in which a waveguide is immersed in a fluid or embedded in a solid. The paper presents the principles of a procedure and then validates and illustrates its use on some examples. The procedure makes use of absorbing regions of material at the exterior bounds of the discretized domain.
147 citations
TL;DR: This paper presents an evolution of the semianalytical finite element method, and gives examples that illustrate new improvements and their importance for studying the propagation of waves along periodic structures of infinite width.
Abstract: The dispersion curves for guided waves have been of constant interest in the last decades, because they constitute the starting point for NDE ultrasonic applications. This paper presents an evolution of the semianalytical finite element method, and gives examples that illustrate new improvements and their importance for studying the propagation of waves along periodic structures of infinite width. Periodic boundary conditions are in fact used to model the infinite periodicity of the geometry in the direction normal to the direction of propagation. This method allows a complete investigation of the dispersion curves and of displacement ∕ stress fields for guided modes in anisotropic and absorbing periodic structures. Among other examples, that of a grooved aluminum plate is theoretically and experimentally investigated, indicating the presence of specific and original guided modes.
107 citations