Abstract Geometrical complexity in truss structures yields large bounding surfaces to be approximated during additive manufacturing (AM) processes. In material extrusion, approximation of geometries using finite-sized thin filaments introduces defects such as voids and gaps in as-fabricated geometries. These can serve as crack initiation sites and increase possibility of fracture by crack propagation. As a result, a truss structure fabricated by material extrusion tends to fail at significantly lower stress than estimated strength without consideration of fracture mechanisms. In this paper, we propose a strength estimation framework for truss structures fabricated by material extrusion that is based on process modeling simulation and a cohesive zone model (CZM). The proposed method assesses two failure criteria: elastic failure and fracture. To evaluate geometrical characteristics of initial cracks embedded by layer-by-layer deposition process, a two-layer deposition model is generated using process modeling simulation. The effective interlayer-bonding strength is estimated based on a cohesive zone model analysis and double cantilever beam (DCB) tests. Resulting embedded crack length and interlayer-bonding strength is integrated into the strength-estimation procedure.

中文翻译：

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基于沉积模型和内聚区模型的材料挤压桁架结构失效估计

摘要 桁架结构中的几何复杂性会在增材制造 (AM) 过程中产生要近似的大边界表面。在材料挤出中，使用有限尺寸的细丝近似几何形状会引入缺陷，例如制造的几何形状中的空隙和间隙。这些可以作为裂纹萌生点并通过裂纹扩展增加断裂的可能性。因此，在不考虑断裂机制的情况下，通过材料挤压制造的桁架结构往往会在比估计强度低得多的应力下失效。在本文中，我们提出了一种基于过程建模模拟和内聚区模型 (CZM) 的材料挤压制造的桁架结构强度估计框架。所提出的方法评估两个失效标准：弹性失效和断裂。为了评估逐层沉积过程嵌入的初始裂纹的几何特征，使用过程建模模拟生成了两层沉积模型。有效层间结合强度是基于内聚区模型分析和双悬臂梁 (DCB) 测试估算的。由此产生的嵌入裂纹长度和层间结合强度被整合到强度估计程序中。