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Ultrahigh frequency vibration control in a piezoelectric phononic crystal beam at the nanoscale considering surface effects

Zhang Zexin, Qian Denghui, Ren Long, Wang Qi

Journal of Theoretical and Applied Mechanics

2024

Vol. 62 nr 1

19--30

In this paper, a piezoelectric phononic crystal beam at the nanoscale has been mechanically modeled by using the surface piezoelectric theory. The band gap has been calculated by the plane wave expansion method and the band gap structure picture has been analyzed. The influence of electromechanical coupling effects, surface effects and geometry on the band gap properties are discussed separately. This study contributes positively to the design and active control of nanoelectromechanical systems.

Investigation on the anti-penetration performance of UD - three-dimensional orthogonal woven fabric composite reinforced structure

Shen Chaoming, Chen Yang, Liu Lei, Zhang Zexin, Tang Baijian, Li Fushan, Qian Denghui

Journal of Theoretical and Applied Mechanics

2023

Vol. 61 nr 4

701--714

A uni-direction (UD) laminate and three-dimensional (3D) orthogonal woven fabric made of ultra high molecular weight polyethylene (UHMWPE) are used as main reinforced units combined with aluminum alloy plates to form a reinforced sandwich structure. Penetration tests are carried out on four composite reinforced structures with different structure forms by a 7.62 mm steel core projectile. The target plate size is 150 mm×150 mm. Besides, Ansys/LS -Dyna software is applied to simulate the penetration process, and the simulation results are in good agreement with the test results. All the results demonstrate that with the same total thickness of UD laminates, 20 mm UD laminates have better penetration resistance than four 5 mm UD laminates. The less the number of UD laminates, the better anti-penetration performance of the overall structure. The 3D orthogonal woven fabric has the advantage of spatial integrity, which can effectively restrain deformation of laminates and absorb energy behind UD laminates, so as to obtain better anti-penetration performance. In the core structure with a total thickness of 28 mm, when the thickness ratio of 3D orthogonal woven fabric is between 30% and 35%, the protection ability and lightweight requirements of the sandwich structure can be better considered.