Process analysis of pseudo-plastic deformation behavior of unidirectional reinforced staple fiber organic sheets

单向增强短纤维有机片材假塑性变形行为过程分析

• 批准号: 471480678
• 负责人: Professor Dr.-Ing. Peter Mitschang
• 金额: --
• 依托单位: Leibniz-Institut für Verbundwerkstoffe (IVW)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/471480678?language=en
• 关键词: Process; analysis; pseudo; plastic; deformation

Continuously fiber-reinforced thermoplastics, so-called organic sheets, are mechanically high-performance semi-finished products, which are processed very economically into shell-shaped components in an efficient thermoforming process. However, the limited drapability of the fiber reinforcement results in comparatively limited geometric component complexity. Organic sheets with continuous carbon or glass fiber reinforcement do not exhibit plastic deformation behavior, since loading of the continuous fibers almost certainly leads to material failure due to the low elongation at fracture. Using staple fiber yarns provides one approach to solve this problem, as they make it possible to achieve an additional degree of freedom in deformation when thermoforming organic sheets. The staple fiber yarns are made of individual reinforcing fibers (so-called staple fibers) with an approximate length of 60 to 80 mm, which are overlapping at different positions. This provides a specific architecture that - in combination with a highly viscous thermoplastic matrix - results in a composite material, in which the individual reinforcing fibers can slide off from each other in the molten state of the matrix. This occurs due to the tensile stress applied in the longitudinal direction of the yarn. In technical terms, this means, that staple fiber organic sheets are pseudo-plastically deformable in the molten state. For the first time, this makes deep-drawing forming possible as it is currently known in metal sheet processing. The project focusses on qualifying the use of staple fiber yarns (made from recycled carbon fibers) in producing organic sheets, as well as on evaluating their processing in the thermoforming process. The fiber ondulation, caused by the production process, requires to be minimized in two process stages, thus improving the process behavior and mechanical properties of staple fiber organic sheets. First, an actively stretched staple fiber tape is produced, which is further processed into organic sheets in the tape laying process with further improvements of the single fiber orientation. These staple fiber organic sheets are analyzed in detail with regard to their pseudo-plastic material behavior. For this purpose, basic research is required for a consistent description of the material and process behavior from tape production to pseudo-plastic deformation in the thermoforming process. In order to investigate the basic mechanisms of pseudo-plastic material behavior, the investigations focus specifically on the behavior of unidirectional staple fiber organic sheets. If this research is successful, an extension to multidirectional laminates, as well as tool and specific thermoforming influences, will be explored in follow-up projects.

连续纤维增强的热塑性塑料（所谓的有机板）是机械性高性能的半成型产品，在有效的热形成过程中，它们在经济上非常经济地处理成壳形组件。但是，纤维增强的有限垂体性导致几何成分复杂性相对有限。带有连续碳或玻璃纤维增​​强的有机板不会表现出塑性变形行为，因为连续纤维的负载几乎可以肯定会导致裂缝伸长率低而导致物质故障。使用钉纤维纱线提供了一种解决此问题的方法，因为它们可以在热成型有机板上实现额外的变形自由度。主食纤维纱是由单个加固纤维（所谓的主食纤维）制成的，其长度约为60至80 mm，它们在不同位置重叠。这提供了一种特定的结构，该结构与高粘性的热塑性矩阵结合使用，形成了复合材料，在该材料中，单个增强纤维可以在基质的熔融状态下彼此滑落。这是由于在纱线的纵向方向上施加的拉伸应力。用技术术语来说，这意味着主纤维有机板在熔融状态下是伪层变形的。这是第一次使深度绘制形成成为可能，因为当前在金属薄板处理中已知。该项目的重点是限定使用钉纤维纱（由再生碳纤维制成的）在产生有机板上以及在热形成过程中评估其加工时的使用。由生产过程引起的纤维爆发需要在两个过程阶段最小化，从而改善了钉书夹纤维有机板的过程行为和机械性能。首先，产生了积极拉伸的主食纤维胶带，并在胶带铺设过程中进一步加工成有机板，并进一步改进单纤维方向。这些主食纤维有机板对其伪塑料材料行为进行了详细分析。为此，需要对从磁带生产到伪塑料变形的材料和过程行为的一致描述进行基础研究。为了研究伪塑料材料行为的基本机制，该研究专门针对单向主食有机板的行为。如果这项研究成功，将在后续项目中探索多向层压板以及工具和特定的热成型影响的扩展。