发表机构
Bundesanstalt für Materialforschung und -prüfung (BAM); Eindhoven University of Technology（联邦材料研究与测试研究所; 埃因霍温理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出结合光滑莫尔-库仑屈服面与非线性各向同性硬化的有限元框架，通过切线刚度特征值准则评估3D打印混凝土的可建造性，准确预测墙体倒塌并揭示直径与硬化速率的影响。
AI 中文摘要
基于挤出的3D混凝土打印无需模板即可逐层建造结构构件，因此新沉积的材料必须在结构强度与刚度尚在增长的同时承受结构不断增加的重量。在失效前可打印的最大层数，即可建造性，是工艺设计的核心。其预测首先取决于本构模型对新鲜混凝土的表示精度。现有的有限元框架仅将渐进的失效前硬化与光滑屈服面结合，这使得最能描述新鲜混凝土的莫尔-库仑屈服面仅限于理想塑性。本工作将光滑的莫尔-库仑屈服面与黏聚力的非线性各向同性硬化相结合，在更新的拉格朗日设置中通过层沉积的激活场进行表述。失效通过切线刚度特征值准则识别，该准则与细长墙体的解析自重屈曲载荷相匹配，且对几何缺陷不敏感。该框架在单层范围内重现了打印直墙的实测倒塌，并预测了空心圆柱的倒塌，其结果比现有框架更接近实验。一项涵盖六种直径和六种硬化速率的研究表明，可建造性在中等直径处达到峰值，并随硬化速率的提高而增加。记录材料在失效时已使用的强度比例，细长圆柱失效时仍有大量强度储备，而中等直径圆柱则几乎用尽全部强度。因此，这两种失效模式被视为同一过程的两个极限，而非独立的失效机制。
英文摘要
Extrusion-based 3D concrete printing builds structural elements layer upon layer without formwork, so freshly deposited material must carry the growing weight of the structure while it is still gaining strength and stiffness. The largest number of layers that can be printed before failure, the buildability, is therefore central to process design. Its prediction rests above all on how accurately the constitutive model represents fresh concrete. Existing finite element frameworks pair gradual pre-failure hardening only with smooth yield surfaces, which leaves the Mohr-Coulomb surface that best describes fresh concrete restricted to perfect plasticity. This work combines a smoothed Mohr-Coulomb yield surface with nonlinear isotropic hardening of the cohesion, formulated in an updated Lagrangian setting with an activation field for layer deposition. Failure is identified from a tangent-stiffness eigenvalue criterion that matches the analytical self-weight buckling load of a slender wall and is insensitive to geometric imperfection. The framework reproduces the measured collapse of a printed straight wall within one layer and predicts the collapse of a hollow cylinder closer to experiment than existing frameworks. A study over six diameters and six hardening rates shows buildability peaking at intermediate diameters and rising with the hardening rate. Recording how much of its strength the material has used at failure, slender cylinders fail with much still in reserve while intermediate ones use nearly all of it. The two failure modes are therefore identified as the limits of one process rather than separate failure mechanisms.
