Additive manufacturing with fibre-reinforcement – design guidelines and investigation into the influence of infill patterns

Abstract

Purpose Fibre-reinforced additive manufacturing (FRAM) with short and continuous fibres yields light and stiff parts and thus increasing industry acceptance. High material anisotropy and specific manufacturing constraints shift the focus towards design for AM (DfAM), particularly on toolpath strategies. Assessing the design-property-processing relations of infill patterns is fundamental to establishing design guidelines for FRAM. Design/methodology/approach Subject to the DfAM factors performance, economy and manufacturability, the efficacy of two conventional infill patterns (grid and concentric) was compared with two custom strategies derived from the medial axis transformation (MAT) and guided by the principal stresses (MPS). The recorded stiffness and strength, the required CPU and print time, and the degree of path undulation and effective fibre utilisation (minimum printable fibre length) associated with each pattern, served as assessment indices for different case studies. Moreover, the influence of material anisotropy was examined, and a stiffness-alignment index was introduced to predict a pattern’s performance. Findings The highest stiffnesses and strengths were recorded for the MPS infill, emphasising the need for tailoring print paths rather than using fixed patterns. In contrast to the grid infill, the concentric infill offered short print times and reasonable utilisation of continuous fibres. The MAT-based infill yielded an excellent compromise between the three DfAM factors and experimentally resulted in the best performance. Originality/value This constitutes the first comprehensive investigation into infill patterns under DfAM consideration for FRAM, facilitating design and processing choices.

Load-Oriented Nonplanar Additive Manufacturing Method for Optimized Continuous Carbon Fiber Parts

“…After experimental evaluation, they came to the conclusion that a load-oriented approach is essential for good mechanical performance, which is currently not offered by any commercial software. Based on this observation, which has been validated by several other publications [ 10 , 11 , 12 ], the following will concentrate on load-oriented approaches. The most popular method in this regard is the utilization of finite-element-analysis (FEA) with carefully selected boundary conditions to obtain a stress distribution.…”

A Comparative Investigation of the Reliability of Biodegradable Components Produced through Additive Manufacturing Technology

“…This suggests that the crack weakens the material’s overall strength. As highlighted by Janos Plocher et al [ 43 ], the presence of a crack acts as a stress concentrator, amplifying stress levels around the crack area beyond what would typically occur in a crack-free material. This stress concentration contributes to the reduced stiffness and strength observed in the cracked sample.…”

“…Considering 3D-printed components produced through FDM as laminate composite structures renders traditional failure models, like Tresca, unsuitable. The application of the Tsai-Wu model involves conceptualizing each layer formed in the 3D printing process as a thin plate experiencing plane stress [ 41 , 42 , 43 ], utilizing the classical orthotropic laminate model. The fundamental assumption entails the presence of a failure surface defined by Equation (13), where the factors F ij are defined as per Equation (14) [ 39 ]: …”

Single-filament-wide tensile-testing specimens reveal material-independent fibre-induced anisotropy for fibre-reinforced material extrusion additive manufacturing

“…As fibres were highly aligned in the printed filaments, the filament orientation directly affect fibre orientation and ultimate properties (Yan et al , 2021), which emphasises the need to fully control filament orientation to obtain effective upper and lower bounds of composite properties. Complex infills may also induce mechanical weakness (Plocher et al , 2022). The structural defects like inter-filament voids may generate stress concentration.…”