Liber-Kneć Aneta, Łagan Sylwia
Faculty of Mechanical Engineering, Department of Applied Mechanics and Biomechanics, Cracow University of Technology, al. Jana Pawła II 37, 31-864 Kraków, Poland.
Interdisciplinary Center for Circular Economy, Cracow University of Technology, ul. Warszawska 24, 31-155 Kraków, Poland.
Materials (Basel). 2025 Jul 10;18(14):3262. doi: 10.3390/ma18143262.
(1) Background: Optimizing infill density in 3D-printed PLA parts reduces material usage, cost, and waste. This study examines mechanical behavior in the initial and hydration stages. The findings provide valuable data for numerical simulations and engineering applications in additive manufacturing. (2) Methods: PLA specimens were printed with infill densities of 100%, 75%, and 25%. Mechanical tests, including tensile and compression tests, and one-hour stress-relaxation at 2% strain were conducted. The digital image correlation method was used to obtain the strain fields on the samples' surface under tensile loading. Mechanical properties, including the elastic modulus, strength values, and Poisson's ratio, were assessed. Hydrolytic degradation effects over one month were also evaluated. (3) Results: Lowering the PLA infill density reduced the ultimate tensile strength (from 60.04 ± 2.24 MPa to 26.24 ± 0.77 MPa), Young's modulus (from 2645.05 ± 204.15 MPa to 1245.41 ± 83.79 MPa), compressive strength (from 26.59 ± 0.80 MPa to 21.83 ± 1.01 MPa), and Poisson's ratio (from 0.32 to 0.30). A 40% mass reduction (form 100% to 25% infill density) resulted in a 56% decrease in tensile strength and a 53% decrease in Young's modulus. A 31% mass reduction was observed for compression samples. Stress relaxation decreased significantly from 100% to 75% density, with further reductions having minimal impact. Hydrated samples showed no mechanical changes compared to baseline specimens. (4) Conclusions: Optimizing infill density in 3D-printed PLA parts helps to balance mechanical performance with material efficiency. The best mechanical properties are typically achieved with an infill density of 100%, but results show that decreasing the mass of the part by a reduction in infill density from 75% to 25% does not significantly affect the ability to transfer tensile and compression loads. PLA's biodegradability makes it a viable alternative to stable polymers. By minimizing material waste and enabling the efficient use of resources, additive manufacturing aligns with the principles of a closed-loop economy, supporting sustainable development.
(1) 背景：优化3D打印聚乳酸（PLA）部件的填充密度可减少材料使用量、成本和浪费。本研究考察了其在初始阶段和水化阶段的力学行为。研究结果为增材制造中的数值模拟和工程应用提供了有价值的数据。(2) 方法：以100%、75%和25%的填充密度打印PLA试样。进行了包括拉伸和压缩试验以及在2%应变下的一小时应力松弛试验。采用数字图像相关方法获取拉伸载荷下样品表面的应变场。评估了包括弹性模量、强度值和泊松比在内的力学性能。还评估了一个月内的水解降解效应。(3) 结果：降低PLA填充密度会降低极限抗拉强度（从60.04±2.24兆帕降至26.24±0.77兆帕）、杨氏模量（从2645.05±204.15兆帕降至1245.41±83.79兆帕）、抗压强度（从26.59±0.80兆帕降至21.83±1.01兆帕）和泊松比（从0.32降至0.30）。质量减少40%（从100%填充密度降至25%填充密度）导致抗拉强度降低56%，杨氏模量降低53%。压缩试样的质量减少了31%。应力松弛从100%密度显著降低到75%密度，进一步降低的影响最小。与基线试样相比，水化试样未显示出力学变化。(4) 结论：优化3D打印PLA部件的填充密度有助于在力学性能和材料效率之间取得平衡。通常填充密度为100%时可获得最佳力学性能，但结果表明，将填充密度从75%降至25%来减少部件质量，不会显著影响传递拉伸和压缩载荷的能力。PLA的生物降解性使其成为稳定聚合物的可行替代品。通过最大限度减少材料浪费并实现资源的高效利用，增材制造符合闭环经济原则，支持可持续发展。
