Modelling damage and residual indentation from composites impact

模拟复合材料冲击造成的损坏和残留压痕

• 批准号: 428994763
• 负责人: Professor Dr.-Ing. Peter Middendorf
• 金额: --
• 依托单位: Institut für Flugzeugbau (IFB)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428994763?language=en
• 关键词: Modelling; damage; residual; indentation; composites

Damage tolerance is a major concern with composite laminates. For low velocity impact external damage may be invisible, or barely visible, whereas significant internal damage may have occurred. In order to assess this, the Compression strength After Impact (CAI) test has been developed and is the industry standard to experimentally quantify loss in strength of a composite laminate after damage from low velocity impact. Essentially, this test impacts plates with various levels of low energy. The plate with a 0.5mm indent is selected, and loaded under edgewise compression to failure. This failure load gives the residual strength after impact which must exceed the maximum structural design load; thus a structure is proven safe to fly with barely visible damage.Numerous researchers have investigated the CAI test to numerically predict intra- and inter-ply damage during impact. A few researchers, including IFB, have also had limited success to couple impact damage modelling with post-impact compression strength analysis. Despite these efforts one important aspect has been overlooked to date; namely, to predict local indentation accurately with respect to impact energies. This is not a trivial problem; it will require 3D modelling and constitutive laws for damage, plasticity and relaxation after load removal; also, a strong coupling with accurate prediction of internal damage will be essential. This is the aim of this research proposal. An extensive materials test program will be undertaken from which new constitutive models will be developed to characterise the local impact crushing and time dependent relaxation unloading of locally impacted composites. The work would advance general scientific knowledge of interaction between surface and internal damage due to low velocity impact and would be an essential step toward a full virtual simulation methodology for the CAI test procedure. Although research will focus on the CAI test configuration the topic is relevant to many other applications involving relatively low impact; for example hailstone impact with wind turbine blades and general impact of foreign bodies against composite laminates.

损伤容限是复合材料层合板的一个主要问题。对于低速撞击，外部损伤可能是看不见的，或几乎看不见的，而严重的内部损伤可能已经发生。为了评估这一点，已经开发了冲击后压缩强度（CAI）测试，并且该测试是通过实验量化复合层压板在低速冲击损坏后的强度损失的行业标准。基本上，该测试以各种低能量水平冲击板。选择具有0.5mm直径的接骨板，并在沿边压缩下加载至失效。该失效载荷给出了冲击后的剩余强度，该强度必须超过最大结构设计载荷;因此结构被证明是安全的，几乎看不到损伤。许多研究人员已经研究了CAI测试，以数值预测冲击过程中的层内和层间损伤。包括IFB在内的一些研究人员在将冲击损伤建模与冲击后压缩强度分析相结合方面也取得了有限的成功。尽管有这些努力，一个重要的方面已被忽视的日期，即准确地预测当地压痕的冲击能量。这不是一个微不足道的问题;它需要三维建模和本构关系，用于损伤、塑性和载荷移除后的松弛;此外，与内部损伤的准确预测的强耦合将是必不可少的。这就是本研究提案的目的。一个广泛的材料试验计划将进行新的本构模型将开发，以模拟局部冲击复合材料的局部冲击破碎和随时间变化的松弛卸载。这项工作将推进一般的科学知识之间的相互作用的表面和内部的损害，由于低速冲击，并将是一个完整的虚拟仿真方法的CAI测试程序的重要一步。尽管研究将集中在CAI测试配置上，但该主题与涉及相对低冲击的许多其他应用相关;例如，冰雹对风力涡轮机叶片的冲击以及异物对复合材料层压板的一般冲击。