The Fused Filament Fabrication is a 3D printing technology that allows the production of components and structures with complex geometries at low-cost, using thermoplastic materials as feedstock. This additive manufacturing technique is not yet extensively used in industries mainly due to parts’ anisotropy – which is the consequence of the deposition strategy – and residual stresses, caused by successive heating cycles. Thus, these topics have great influence on the non-linear mechanical performance of 3D printed parts. Additionally, the materials used in the Fused Filament Fabrication have distinct mechanical behaviours under tensile and compression loads. This work proposes a computational framework – using a meshless method as the numeric discretization technique, the Natural Neighbour Radial Point Interpolation method – capable to analyse the elastoplastic response of ductile materials showing distinct compressive and tensile responses, through the implementation of a modified version of the Hill yield surface. In those conditions, 3D-printed specimens of polylactic acid are tested experimentally and numerically using standard tensile and compression tests. The numerical approach is validated by comparing the numerical and the experimental curves. Then, the accuracy of the methodology is proved and the purpose of using the modified Hill yield criterion is clearly shown using a benchmark example.

熔融长丝加工是一种3D打印技术，可使用热塑性材料作为原料，以低成本生产具有复杂几何形状的组件和结构。这种增材制造技术尚未在工业中得到广泛应用，这主要是由于零件的各向异性（这是沉积策略的结果）以及由连续加热周期引起的残余应力的结果。因此，这些主题对3D打印部件的非线性机械性能有很大影响。另外，熔融长丝加工中使用的材料在拉伸和压缩载荷下具有独特的机械性能。这项工作提出了一个计算框架-使用无网格方法作为数值离散技术，自然邻居径向点插值方法–通过实施希尔屈服面的改进版本，能够分析表现出明显压缩和拉伸响应的延性材料的弹塑性响应。在这些条件下，使用标准拉伸和压缩测试对3D打印的聚乳酸样品进行实验和数字测试。通过比较数值曲线和实验曲线来验证数值方法。然后，证明了该方法的准确性，并通过一个基准示例清楚地说明了使用修改后的希尔产量准则的目的。使用标准拉伸和压缩测试对3D打印的聚乳酸样品进行实验和数字测试。通过比较数值曲线和实验曲线来验证数值方法。然后，证明了该方法的准确性，并通过一个基准示例清楚地说明了使用修改后的希尔产量准则的目的。使用标准拉伸和压缩测试对3D打印的聚乳酸样品进行实验和数字测试。通过比较数值曲线和实验曲线来验证数值方法。然后，证明了该方法的准确性，并通过一个基准示例清楚地说明了使用修改后的希尔产量准则的目的。