Design guidelines for hybrid continuous/discontinuous carbon fibre laminates
Design guidelines for hybrid continuous/discontinuous carbon fibre laminates
复制标题
混合连续/不连续碳纤维层压板的设计指南
DOI：
10.1177/00219983221078786
复制
发表时间：
2022
影响因子：
2.9
通讯作者：
Evans A
中科院分区：
文献类型：
--
作者：
Evans A
人们已经研究了将不连续碳纤维模塑料与单向（UD）无卷曲织物相结合，作为生产具有成本效益的复合结构的潜在解决方案，并通过压缩成型缩短周期时间。当 20%（体积比）的 UD 纤维沿主载荷方向排列时，具有混合纤维结构的复合材料的拉伸刚度和强度分别比基线不连续纤维模塑料高 60% 和 110%。然而，如果未有效结合单向纤维，不同材料特性产生的应力集中可能会导致混合结构的强度降低至低于基准复合材料的强度。本文重点讨论当使用局部隔离的连续纤维而不是全覆盖层时，UD 材料和不连续纤维模塑料之间的过渡区域（材料间界面）内的应力传递。如果要在结构应用中采用混合架构，最大限度地减少单向层层端部的应力集中效应，同时保持与压缩成型相关的低周期时间和成本，这一点至关重要。遵循航空航天层压板设计指南，针对不同的层板下降策略考虑了一系列步长尺寸和接头配置，从而最大限度地减少单向层板端部的应力集中程度。结果表明，步长必须至少为 UD 层厚度的 20 倍，以确保接头处的弯曲强度与基线不连续纤维材料相同。 “交替接头”的弯曲强度比传统的“阶梯式接头”设计高 18%，因为与不连续纤维材料内的固有应力集中相比，掉落层端部的应力集中减少了。
Combining discontinuous carbon fibre moulding compounds with unidirectional (UD) non-crimp fabric has been studied as a potential solution for producing cost effective composite structures, with short cycle times via compression moulding. The tensile stiffness and strength of a composite with a hybrid fibre architecture were found to be up to 60% and 110% higher, respectively, than the baseline discontinuous fibre moulding compound, when 20% (by vol.) of UD fibres were aligned in the primary loading direction. However, stress concentrations arising from the dissimilar material properties can result in the strength of the hybrid architecture being reduced to below that of the baseline composite if the UD fibres are not incorporated effectively. This paper focusses on optimising the stress transfer within the transition zone (inter-material interface) between the UD material and the discontinuous fibre moulding compound, when local isolated patches of continuous fibre are used rather than full coverage plies. This is key if hybrid architectures are to be adopted for structural applications, minimising the stress concentration effects from the UD ply ends, whilst maintaining the low cycle times and costs associated with compression moulding. Following aerospace laminate design guidelines, a range of step sizes and joint configurations have been considered for different ply drop strategies, minimising the magnitude of the stress concentration at the UD ply ends. Results indicate that the step length must be at least 20 times the thickness of the UD ply to ensure the bending strength at the joint is the same as the baseline discontinuous fibre material. An ‘alternating joint' yields 18% higher bending strengths than a conventional ‘stepped joint’ design, as the stress concentrations at the dropped ply ends are reduced in comparison to the inherent stress concentrations within the discontinuous fibre material.
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作者：
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影响因子：
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DOI：
10.1016/j.compositesa.2005.12.028
发表时间：
2006
影响因子：
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