Numerical analysis of impact resistance of honeycomb structures with different Poisson's ratios北大核心CSCD

［Objectives］This papers aims to analyze the impact resistance of honeycomb structure with different Poisson's ratio. ［Methods］Based on the explicit dynamic finite element method, this paper analyzes the dynamic mechanical properties of honeycomb structures with different Poisson's ratios under in-plane impact load, and explores the influence laws of Poisson's ratios on their impact resistance. Three typical honeycomb structures with negative/zero/positive Poisson's ratios (reentrant hexagon, hexagon and semi-reentrant hexagon) are selected, their geometric parameters are changed to give them the same relative density and different Poisson's ratios (−2.76 – +3.63), and their dynamic mechanical properties under low/medium/high-speed dynamic displacement loads are analyzed. ［Results ］ The results show that the zero Poisson's ratio semi-reentrant honeycomb structure has the best structural stability without transverse deformation under compression deformation; without structural instability, the platform stress has little correlation with the Poisson's ratio; and the compact strain and total energy absorbtion increases with the absolute value of the Poisson's ratio. Negative Poisson's ratio honeycomb structures with large t/l and small θ are suitable for applications with high platform stress (strong deformation resistance), and negative Poisson's ratio honeycomb structures with small t/l and small θ are suitable for high total energy absorbtion applications, while zero Poisson's ratio semi-reentrant honeycomb structures are suitable for applications with high platform stress (strong deformation resistance). ［Conclusions］This study can provide references for the type selection and geometric parameter design of side impact honeycomb structures. © 2023 Authors. All rights reserved.     

双色波作用下港池长周期波浪模拟研究

防波堤对长周期波浪的掩护较差，长周期波浪容易直接侵袭港内，恶化港内作业条件。依托物理模型试验结果，基于BW数值模型研究双色波作用下港池长周期波浪产生机制。对BW数值模型进行验证，模型与试验结果吻合良好。在频率分别为f₁和f₂的双色波作用下，波浪间发生非线性作用产生Δf、2f₁-f₂、2f₂-f₁、2f₁、f₁+f₂、2f₂等频率的波浪，当产生的长周期波浪Δf与港口自振频率趋于一致时，长周期波浪波高被港池捕捉发生共振而放大。随着双色波入射波高、调谐率的增加，波浪之间的非线性作用增强，长周期波高显著增大。