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    Non-destructive evaluation of a composite honeycomb sandwich panel with in-plane waviness damage using ultrasonic guided waves
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    Abstract:
    Composite honeycomb sandwich structures (CHSS) are often manufactured using an autoclave co-cure process, which can introduce in-plane waviness (IW) damage due to fibre misalignment. Such fibre waviness, whether in-plane or out-of-plane, significantly weakens the strength of these structures. Therefore, developing reliable non-destructive evaluation (NDE) techniques is essential for detecting IW. This study presents an NDE technique utilising ultrasonic guided waves (GW) to identify IW damage in CHSS panels. A numerical model was created using COMSOL Multiphysics, where IW damage is simulated through curvilinear coordinate physics, followed by a time-dependent study of GW propagation. This model simulates local fibre orientation changes due to IW damage, enhancing our understanding of GW interaction with IW. Experimental investigations are performed using contact-type transducers to corroborate the numerical observations. The presence of in-plane waviness causes a reduction in the group velocity of the A0 mode, a characteristic that can be exploited for detecting in-plane fibre waviness in CHSS. Also, parametric studies were performed to examine the effects of IW severity (aspect ratio) and increased IW area on GW characteristics. Finally, a technique for IW damage localisation is demonstrated using a convex hull algorithm based on changes in correlation coefficient values of the A0 mode.
    Keywords:
    Waviness
    Honeycomb
    Honeycomb structure
    Sandwich panel
    Many industries use honeycomb composites extensively, including the aerospace, automotive, furniture, packaging, and logistic sectors. A specific type of composite material known as a honeycomb sandwich is created by joining two stiff but thin skins to a lightweight but dense core. The sandwich composite strong bending stiffness and overall low density are made possible by the core material's larger thickness despite its typical low strength. The Sandwich panel's strength is influenced by the panel's size, the material chosen for the faceplates, and the density of the honeycomb cells inside. This study investigates the critical buckling stresses numerically for different core densities and materials of honeycomb composite panels. In this investigation, the faceplate material is constant while the core material varies. It can be observed that when core density increases, so do the specimens buckling strength. Analytical investigations on honeycomb sandwich panels are used to examine the behavior of sinusoidal and hexagonal honeycomb sandwich panels under impact loads. LS-DYNA was used for analysis, and HYPER-MESH was used for modeling.
    Honeycomb
    Honeycomb structure
    Sandwich panel
    Specific strength
    Specific modulus
    Honeycomb structures have recently, replaced with conventional homogeneous materials. Given the fact that sandwich panels containing a honeycomb core are able to adjust geometric parameters, including internal angles, they a... | Find, read and cite all the research you need on Tech Science Press
    Honeycomb
    Sandwich panel
    Honeycomb structure
    Sound transmission class
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    The star-shaped concave structure material is a new type of negative Poisson’s ratio material, which combines the advantages of negative Poisson’s ratio material and honeycomb material. The negative Poisson’s ratio structure has very good mechanical properties, such as bearing capacity, impact resistance, and shear resistance. The honeycomb sandwich panel is a typical lightweight material with high specific strength, specific stiffness, and good energy absorption characteristics. In this paper, the star-shaped concave structure is used as the core layer of the sandwich panel, and the advantages of both the honeycomb sandwich panel and negative Poisson’s ratio structure are combined to make a star-shaped honeycomb sandwich panel. In order to analyze the properties of this material, we use the finite element numerical simulation method to study the effects of several geometric parameters (element thickness, beam width, beam length, and star angle) on the bending stiffness, buckling critical load and natural frequency of honeycomb sandwich panels, which provides a new reference for the design optimization of star-shaped concave honeycomb sandwich panels in practical engineering applications.
    Honeycomb
    Sandwich panel
    Honeycomb structure
    Auxetics
    Poisson's ratio
    Star (game theory)
    Specific modulus
    Sandwich panel which has a design involving acoustic comfort is always denser and larger in size than the design involving mechanical strength. The respective short come can be solved by exploring the impact of core geometry on sound transmission characteristics of sandwich panels. In this aspect, the present work focuses on the study of influence of core geometry on sound transmission characteristics of sandwich panels which are commonly used as aircraft structures. Numerical investigation has been carried out based on a 2D model with equivalent elastic properties. The present study has found that, for a honeycomb core sandwich panel in due consideration to space constraint, better sound transmission characteristics can be achieved with lower core height. It is observed that, for a honeycomb core sandwich panel, one can select cell size as the parameter to reduce the weight with out affecting the sound transmission loss. Triangular core sandwich panel can be used for low frequency application due to its increased transmission loss. In foam core sandwich panel, it is noticed that the effect of face sheet material on sound transmission loss is significant and this can be controlled by varying the density of foam.
    Sound transmission class
    Sandwich panel
    Honeycomb structure
    Honeycomb
    Transmission loss
    Soundproofing
    Citations (53)
    The double honeycomb sandwich panel, which was formed by inserting an intermediate facesheet into single honeycomb core, showed better capability than single honeycomb panel in shielding hyper-velocity impact from space debris. Shielding structures with double honeycomb cores are thor- oughly investigated with material point method and point-based internal-structure model. The front hon- eycomb core and the rear honeycomb core are staggered to obtain better shielding effect. It is found that staggered double honeycomb cores can fragment the debris and lessen impact threats much more than original double honeycomb cores. The sizes of the holes on the rear facesheet are greatly reduced, and the panels are not perforated for some impact velocities. Staggered double honeycomb panels can be adopted as novel effective shielding structures for hyper- velocity impacts.
    Honeycomb
    Honeycomb structure
    Sandwich panel
    Citations (1)