航空航天轻量化结构通常需兼具减重、承载、减振、抗冲击等多种性能要求。但结构在减重的同时往往会伴随着承载、抗冲击性能的降低。基于变密度法对圆锥结构进行了拓扑优化设计,并利用激光粉末床熔融技术实现了圆锥轻量化构件一体化成形,研究了轴向压缩试验下壁厚对拓扑优化构件力学性能的影响机制。试验结果表明,随着壁厚由 1.0 mm 增至 3.0 mm,结构的比吸能先增后减,壁厚 2.5 mm 的构件比吸能最大,为 11.48 J/g。采用有限元模拟方法研究了拓扑优化圆锥结构在压缩过程中的应力分布情况,结果表明,构件发生屈曲变形及断裂的主要原因为较大的面内压应力,内外壁应力水平差异导致了结构发生不同方向的屈曲变形,且随着壁厚的增加,圆锥顶部出现的应力集中及上层屈曲程度的降低均导致结构不能持续增加能量吸收。
Abstract
Aerospace lightweight structures usually need to meet various performance requirements
such as weight reduction
load-bearing
shock absorption and impact resistance. However
the weight reduction of structures is often accompanied by the reduction of load-bearing and impact resistance. In this paper
the topology optimization design of conical structures was carried out based on variable density method. And the integrated forming of conical lightweight components was realized by laser powder bed melting technology. The inflfluence mechanism of wall thickness on the mechanical properties of topologically optimized components under axial compression were studied. As the wall thickness increased from 1.0 mm to 3.0 mm
the specifific energy absorption increased fifirstly and then decreased. The component with wall thickness of 2.5 mm exhibited the highest specifific energy absorption
which was 11.48 J/g. The stress distribution during compression was studied by fifinite element simulation
which showed that the main reason for the buckling and fracture of structures was the large in plane compressive stress. The difffference of stress levels between the inner and outer walls led to the buckling deformation of the structure in difffferent directions. And with the increase of wall thickness
the stress concentration at the top of the cone and the reduction of the upper buckling degree terminated the continuous increase of energy absorption.