Understanding Delamination Suppression at High Deformation Rates in Through-Thickness Reinforced Laminated Composites

了解全厚度增强层合复合材料中高变形率下的分层抑制

• 批准号: EP/M015319/1
• 负责人: Stephen Hallett
• 金额: $ 47.8万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FM015319%2F1
• 关键词: Understanding; Delamination; Suppression; Deformation; Rates

This proposal focuses on the impact performance of state-of-the-art composites in the form of fibre-reinforced plastics (FRPs) with through-thickness reinforcement introduced via Z-pinning. The application of composites in primary lightweight structures has been steadily growing during the last 20 years, increasing the requirement for new and advanced composites technologies. Recent examples include large civil aircraft, such as the Boeing 787 and the Airbus A350, high performance cars, such as the McLaren 650S, and civil infrastructure, such as the Mount Pleasant bridge on the M6 motorway. FRPs are made of thin layers (plies) of plastic material with embedded high stiffness and strength fibres. The plies are bonded together in a stack by applying heat and pressure in a process known as "curing". The resulting assembly is the FRP laminate. The main reasons for the increasing usage of FRPs in several engineering fields are the superior in-plane specific stiffness and strength with respect to traditional alloys and the long-term environmental durability due to the absence of corrosion. Another key advantage of FRPs is that they can be tailored to specific design loads via optimising the orientation of the reinforcing fibres across the laminate stack. FRPs are, however, prone to delamination, i.e. the progressive dis-bond of the plies through the thickness of the laminate. This is due to the fact that standard FRP laminates have no reinforcement in the through-thickness direction, so the out-of-plane mechanical properties are significantly lower than the in-plane ones. According to the US Air Force, delamination can be held responsible for 60% of structural failures in FRP components in service. Impacts are the main cause of delamination in FRP laminates with energies usually in the order of 20J, sufficient to produce multiple delaminations in FRP plates. A representative scenario for such energy level is that of a 2cm diameter stone impacting a laminate at a speed of 110 km/h. In aerospace impact scenarios can be much more severe. For example, the certification of turbofan engines requires the fan blades to be able to withstand an impact with a bird whose mass is in the order of a few kilograms at speed in excess of 300 km/h, with impact energies of thousands of Joules. Introducing through-thickness reinforcement in FRPs is a viable strategy for improving the through-thickness mechanical properties and inhibiting delamination. Z-pinning is a through-thickness reinforcement technique whereby short FRP rods are inserted in the laminate before curing. Z-pinning has been proven to be particularly effective in inhibiting delamination under quasi-static, fatigue loading and low velocity/low energy impact loading. Nonetheless, little is known regarding the performance of Z-pinned laminates withstanding high energy/high speed impacts, whose effects are governed by complex transient phenomena taking place within the bulk FRP laminates and multiple ply interfaces. Overall, these phenomena are commonly denoted as "high strain rate" effects. There is some evidence that Z-pinning is beneficial also for high-speed impacts, but this is not conclusive. The current lack of knowledge may be circumvented with overdesign and expensive large-scale structural testing, but this is not a sustainable solution in a medium to long-term scenario. This project aims to fill the knowledge gap outlined above, by combining novel experimental characterisation at high deformation rates with new modelling techniques that can be used for the design and certification of impact damage tolerant composite structures. The development of suitable modelling techniques is particularly important for industrial exploitation, since it will reduce the amount of testing required for certification of composite structures, with a significant reduction of costs and shorter lead times to mark

这项建议侧重于最先进的纤维增强塑料(FRPS)形式的复合材料的冲击性能，其中通过Z形销引入了贯穿厚度的增强。在过去的20年里，复合材料在一次轻量化结构中的应用一直在稳步增长，这增加了对新的和先进的复合材料技术的要求。最近的例子包括大型民用飞机，如波音787和空中客车A350，高性能汽车，如迈凯轮650S，以及民用基础设施，如M6高速公路上的芒特普莱森大桥。玻璃纤维增强塑料由薄层塑料材料制成，内嵌高硬度和高强度纤维。通过加热和加压，将这些层粘合在一起，这一过程被称为“固化”。最终得到的组件是FRP层压板。FRPS在多个工程领域应用日益广泛的主要原因是相对于传统合金具有更好的面内比刚度和强度，以及由于没有腐蚀而具有长期的环境耐久性。FRPS的另一个关键优势是，通过优化层压叠层中增强纤维的取向，可以根据特定的设计载荷进行定制。然而，FRP容易分层，即层压板厚度的层间逐渐脱键。这是因为标准FRP层合板在贯穿厚度方向上没有配筋，因此平面外的力学性能明显低于平面内的力学性能。根据美国空军的说法，在服役的玻璃钢构件中，60%的结构失效是由分层造成的。冲击是导致FRP层合板分层的主要原因，能量通常在20J量级，足以在FRP板中产生多个分层。这种能级的一个典型场景是直径2厘米的石头以110公里/小时的速度撞击层合板。在航空航天中，撞击场景可能要严重得多。例如，涡扇发动机的认证要求风扇叶片能够承受质量约为几公斤、时速超过300公里、撞击能量为数千焦耳的鸟的撞击。在FRPS中引入穿层加固是提高穿层力学性能和抑制分层的一种可行策略。Z-PING是一种贯穿厚度的加固技术，在固化前将短FRP棒插入层合板中。Z钉扎已被证明在准静态、疲劳加载和低速/低能量冲击加载下特别有效地抑制分层。然而，关于Z销层板抵抗高能/高速冲击的性能知之甚少，其影响是由主体FRP层板和多层界面内发生的复杂的暂态现象决定的。总的来说，这些现象通常被称为“高应变率”效应。有一些证据表明，Z轴定位对高速撞击也是有益的，但这并不是决定性的。目前的知识匮乏可以通过过度设计和昂贵的大规模结构测试来规避，但在中长期情况下，这不是一个可持续的解决方案。该项目旨在通过将新的高变形速率下的实验特征与可用于设计和验证耐冲击损伤复合材料结构的新建模技术相结合，来填补上述知识空白。开发合适的建模技术对工业开发特别重要，因为它将减少复合材料结构认证所需的测试量，显著降低成本和缩短标记的交货期

项目成果

Coupon scale Z-pinned IM7/8552 delamination tests under dynamic loading

• DOI: 10.1016/j.compositesa.2019.105565
• 发表时间: 2019-10
• 期刊: Composites Part A: Applied Science and Manufacturing
• 作者: H. Cui;Yusuf Mahadik;S. Hallett;I. Partridge;G. Allegri;S. Ponnusami;N. Petrinic

Dynamic bridging mechanisms of through-thickness reinforced composite laminates in mixed mode delamination

• DOI: 10.1016/j.compositesa.2017.11.017
• 发表时间: 2018-03
• 期刊: Composites Part A-applied Science and Manufacturing
• 影响因子: 8.7
• 作者: H. Cui;H. Cui;M. Yasaee;S. Hallett;I. Partridge;G. Allegri;N. Petrinic

Inter-fibre failure of through-thickness reinforced laminates in combined transverse compression and shear load

• DOI: 10.1016/j.compscitech.2018.06.011
• 发表时间: 2018-09-08
• 期刊: COMPOSITES SCIENCE AND TECHNOLOGY
• 影响因子: 9.1
• 作者: Cui, Hao;Melro, Antonio R.;Yasaee, Mehdi
• 通讯作者: Yasaee, Mehdi

Experimental investigation of large-scale high-velocity soft-body impact on composite laminates

复合材料层合板大规模高速软体冲击实验研究

• DOI: 10.1016/j.ijimpeng.2021.104089
• 发表时间: 2022
• 期刊: International Journal of Impact Engineering
• 影响因子: 5.1
• 作者: Cochrane A

Rate-Dependent Modelling of the Meso-Mechanics of Z-Pins Bridging Mixed Mode Delaminations

Z 销桥接混合模式分层的细观力学的速率相关建模

• 发表时间: 2018
• 作者: Hijazi H