Purpose

Fused Filament Fabrication (FFF) is an extrusion-based manufacturing process using fused thermoplastics. Despite its low cost, the FFF is not extensively used in high-value industrial sectors mainly due to parts' anisotropy (related to the deposition strategy) and residual stresses (caused by successive heating cycles). Thus, this study aims to investigate the process improvement and the optimization of the printed parts.

Design/methodology/approach

In this work, a meshless technique – the Radial Point Interpolation Method (RPIM) – is used to numerically simulate the viscoplastic extrusion process – the initial phase of the FFF. Unlike the FEM, in meshless methods, there is no pre-established relationship between the nodes so the nodal mesh will not face mesh distortions and the discretization can easily be modified by adding or removing nodes from the initial nodal mesh. The accuracy of the obtained results highlights the importance of using meshless techniques in this field.

Findings

Meshless methods show particular relevance in this topic since the nodes can be distributed to match the layer-by-layer growing condition of the printing process.

Originality/value

Using the flow formulation combined with the heat transfer formulation presented here for the first time within an in-house RPIM code, an algorithm is proposed, implemented and validated for benchmark examples.

中文翻译：

---

径向点插值法数值模拟粘塑性材料挤压过程

目的

熔丝制造 (FFF) 是一种使用熔融热塑性塑料的基于挤出的制造工艺。尽管成本低廉，但 FFF 并未广泛应用于高价值工业领域，这主要是由于零件的各向异性（与沉积策略相关）和残余应力（由连续的加热循环引起）。因此，本研究旨在研究打印零件的工艺改进和优化。

设计/方法论/途径

在这项工作中，使用无网格技术——径向点插值法 (RPIM)——对粘塑性挤压过程——FFF 的初始阶段进行数值模拟。与 FEM 不同，在无网格方法中，节点之间没有预先建立的关系，因此节点网格不会面临网格变形，并且可以通过在初始节点网格中添加或删除节点来轻松修改离散化。所获得结果的准确性凸显了在该领域使用无网格技术的重要性。

发现

无网格方法在本主题中表现出特别的相关性，因为节点可以分布以匹配打印过程的逐层生长条件。

原创性/价值

在内部 RPIM 代码中首次使用流动公式与传热公式相结合，提出了一种算法，并针对基准示例进行了实施和验证。