On the free vibration analysis of laminated composite and sandwich plates: A review of recent literature with some numerical results

An acoustic metasurface carpet cloak based on membrane-capped cavities is proposed and investigated numerically. This design has been chosen for allowing ultrathin geometries, although adapted to airborne sound frequencies in the range of 1 kHz ($\ensuremath{\lambda}\ensuremath{\approx}30$ cm), surpassing the designs reported in the literature in terms of thinness. A formulation of generalized Snell's laws is first proposed, mapping the directions of the incident and reflected waves to the metasurface phase function. This relation is then applied to achieve a prescribed wavefront reflection direction, for a given incident direction, by controlling the acoustic impedance grading along the metasurface. The carpet cloak performance of the proposed acoustic metasurface is then assessed on a triangular bump obstacle, generally considered as a baseline configuration in the literature.

https://link.aps.org/pdf/10.1103/PhysRevB.94.014302

Acoustic carpet cloak based on an ultrathin metasurface

Analytical modeling and vibration analysis of internally cracked rectangular plates

Light-weight sandwich composites can be tailored to satisfy many specific application requirements and are inevitable for modern structures where reduced weight is extremely critical. However, these structures are highly vulnerable to debonding at the skin-core interface. The skin-core adhesion is an extremely crucial part of a sandwich structure; mostly responsible for transferring load and maintaining integrity between the components. Keeping this into consideration, the effectiveness of a straightforward but productive technique of using an additional adhesive layer between the face-sheet and core for improving the damage resistance of sandwich structures is investigated. Contribution of a reinforced skin-core interface via adhesive bonding on the impact and post-impact performances, i.e., the maximum load and energy dissipation capacities and failure modes of the sandwich composites were experimentally investigated. Application of additional adhesive at the skin-core interface while manufacturing CFRP/end-grain balsawood sandwich composite demonstrated improved structural performance with no significant variation in density nor requiring additional complex manufacturing procedures. Experimental methods such as low-energy impact, compression-after-impact (CAI), and core compression tests were utilized to illustrate the influence of the interface enforcement. Experimental results indicate that interface adhesive application reinforces the structure's impact tolerance and improves post-impact response. Controlled skin-core debonding primarily attributes to the improved features.

Influence of interfacial adhesive on impact and post-impact behaviors of CFRP/end-grain balsawood sandwich composites

http://oa.upm.es/15669/1/INVE_MEM_2012_130019.pdf

Multiobjective optimization applied to structural sizing of low cost university-class microsatellite projects

A novel Bessel function method is proposed to obtain the exact solutions for the free-vibration analysis of rectangular thin plates with three edge conditions: (i) fully simply supported; (ii) fully clamped, and (iii) two opposite edges simply supported and the other two edges clamped. Because Bessel functions satisfy the biharmonic differential equation of solid thin plate, the basic idea of the method is to superpose different Bessel functions to satisfy the edge conditions such that the governing differential equation and the boundary conditions of the thin plate are exactly satisfied. It is shown that the proposed method provides simple, direct, and highly accurate solutions for this family of problems. Examples are demonstrated by calculating the natural frequencies and the vibration modes for a square plate with all edges simply supported and clamped.

https://nocweba.ntu.edu.sg/laq_mems/journal%20papers/2007/Exact%20solutions%20for%20free-vibration%20analysis%20of%20rectangular%20plates%20using%20Bessel%20functions.pdf

Hongen Chen

Papers

Exact Solutions for Free-Vibration Analysis of Rectangular Plates Using Bessel Functions

Deformation and failure of hybrid composite sandwich beams with a metal foam core under quasi-static load and low-velocity impact

Ballistic Limit of Sandwich Plates With a Metal Foam Core