Design and mechanical behavior of anti-shock composite protective layer for offshore wind power dynamic cable
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摘要: 针对恶劣海况下动态海缆及其保护套与风机平台摩擦和碰撞导致的断裂问题,以具有高弹性、高缓冲性能的EVA泡沫和橡胶为主体材料,设计了一种抗多次冲击复合防护层。采用万能试验机和落锤,开展了不同加载条件下多种相对密度的EVA泡沫材料的力学性能实验,揭示了相对密度、应变率和多次加载对材料能量吸收特性的影响规律。基于EVA泡沫材料单位体积吸能率与待吸收的动态海缆动能之间的匹配关系,讨论并确定最佳的防护层厚度尺寸,进而制作了复合防护层测试样件。随后,通过落锤冲击实验对复合防护层在单次冲击和多次冲击条件下的缓冲吸能特性进行了研究。实验结果表明,1)在单次冲击下复合防护层的峰值力与最大位移随落锤质量与下落速度呈线性正相关变化,且能量吸收效率高达85 %;2)在多次冲击下复合防护层的力学性能呈现显著稳定性,第四次冲击的最大位移较首次冲击仅增大了5.5 %,且能量吸收值和瞬时回弹率的波动幅度小于5 %。复合防护层的独特力学性能可为动态海缆在恶劣海况下的长期使用提供有效保护。
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关键词:
Abstract: To address the fracture problem of dynamic submarine cables and their protective sheaths caused by friction and collision with wind turbine platforms under harsh sea conditions, a multi-impact resistant composite protective layer was designed using EVA foam and rubber as the main materials, which possess high elasticity and excellent cushioning properties.Mechanical property tests were conducted on EVA foam materials with various relative densities under different loading conditions using a universal testing machine and drop hammer. Energy absorption efficiency, densification strain, plateau stress and maximum specific energy absorption were introduced to characterize the mechanical properties of EVA foam. The effects of relative density, strain rate and repeated loading on the energy absorption characteristics of EVA foam were revealed.Based on the matching relationship between the energy absorption per unit volume of EVA foam and the kinetic energy of dynamic submarine cables to be absorbed, the optimal thickness of the protective layer was determined, and composite protective layer specimens were fabricated. Subsequently, drop hammer impact tests were performed to compare the cushioning and energy absorption characteristics of the composite protective layer with other materials, preliminarily verifying its high energy absorption efficiency.Further drop hammer impact tests were conducted to investigate the effects of impact energy and loading cycles on the cushioning and energy absorption characteristics of the composite protective layer. The experimental results showed that: 1) Under single impact, the peak force and maximum displacement of the composite protective layer showed a linear positive correlation with the drop hammer mass and impact velocity, with energy absorption efficiency reaching 85 %; 2) Under multiple impacts, the mechanical properties of the composite protective layer exhibited remarkable stability - the maximum displacement in the fourth impact increased by only 5.5 % compared to the first impact, with fluctuations in energy absorption value and instantaneous rebound rate remaining below 5 %. The composite protective layer demonstrates unique mechanical properties that provide effective long-term protection for dynamic submarine cables under harsh marine conditions.-
Key words:
- EVA foam /
- quasi-static compression /
- dynamic compression /
- energy absorption /
- cable protection
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