Numerical modelling of armour layers with reference to Core-Loc units and their placement acceptance criteria
Numerical modelling of armour layers with reference to Core-Loc units and their placement acceptance criteria
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参考 Core-Loc 单元及其放置验收标准对装甲层进行数值建模
DOI：
10.1016/j.oceaneng.2015.05.010
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发表时间：
2015
影响因子：
5
通讯作者：
Anastasaki E
中科院分区：
文献类型：
--
作者：
Anastasaki E
Core-Loc装甲层的建造要求根据网格模式系统地放置单位质心。为了给出该单元的开发者所需的互锁类型，完全随机或严格相同取向的相邻布局模式都是不成功的。这意味着需要在单元取向上具有一定程度的不规则性。为了指导承包商，认为已按照可接受标准放置的装甲层，单元必须满足Core-Loc开发商给出的特殊放置标准。缺乏关于如何实现这种“可接受的不规则取向和安置”的指导。建造的成功似乎更多的是起重机操作员的经验和技能的函数，而不是任何可重复的或潜在的机器可编程的方法。因此，设计一种可重复的数值方法来可靠地将单元定位到满足开发人员特殊放置标准的装甲层中也是具有挑战性的。对于全尺寸Core-Loc装甲层的数值创建，作者在以前的工作中简要介绍了一种放置方法，该方法基于多体FEMDEM代码Y3 D-R结合通用沉积代码POSITIT。虽然令人满意的层之前被证明，在这里，我们详细说明了放置的装甲层属性的数值施工工艺参数的敏感性。在这项工作中，POSITIT/Y3 D-R的新功能被利用在一个计算效率高的逐行数字单元布局中。这些措施包括振动和人为的低摩擦，以实现适当包装密度的可接受的不规则包装。要检查的作用，最初的装甲层建设质量上的单位不动性或单位的百分比，不位移显着下一个标准的振荡干扰力，正弦速度振动施加到基础上的一系列测试不同构造的全尺寸装甲层。从这一敏感性研究中得出的结论是对Core-Loc装置开发商所设定的技术要求的重要性的隐含验证。
The construction of Core-Loc armour layers requires that unit centroids are systematically placed according to a grid pattern. To give the type of interlock required by this unit’s developers, neither a fully random nor a strict identically orientated neighbour-to-neighbour pattern of placement is successful. This means that a certain degree of irregularity in unit orientations is required. To guide the contractors, armour layers deemed to have been placed with acceptable standards, units must satisfy special placement criteria given by the Core-Loc developer. There is a lack of instruction on how to achieve such ‘acceptable irregular orientations and placements’. The construction success seems more a function of experience and skill of the crane operator than any repeatable or potentially machine-programmable methodology. For this reason, it is also challenging to design a repeatable numerical method that reliably positions units into armour layers that satisfy the developer’s special placement criteria.For the numerical creation of full-scale Core-Loc armour layers, a placement method was briefly introduced in previous work by the authors, based on the multi-body FEMDEM code, Y3D-R combined with a versatile deposition code, POSITIT. While satisfactory layers were previously demonstrated, here we elaborate on the sensitivity of the placed armour layer attributes to the numerical construction process parameters. In this work, new capabilities of POSITIT/Y3D-R are harnessed in a computationally efficient row-by-row numerical placement of units. These include vibration and artificially low friction in order to achieve acceptable irregular packs of the appropriate packing density. To examine the role that initial armour layer build quality has on unit immovability or the percentage of units that do not displace significantly under a standard oscillatory disturbing force, a sinusoidal velocity vibration is applied to the foundations in a series of tests on differently constructed full-scale armour layers. What emerges from this sensitivity study is an implicit verification of the importance of the technical requirements set by the developer of Core-Loc units.
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