Weihrauch M, Lambert P, Lambros J, Sutcliffe C J, Patterson E A
Department of Mechanical and Aerospace Engineering, University of Liverpool, Liverpool, UK.
Department of Aerospace Engineering, University of Illinois Urbana-Champaign, Urbana, USA.
Exp Mech. 2025;65(4):481-493. doi: 10.1007/s11340-024-01130-5. Epub 2025 Jan 23.
Additively-manufactured parts contain residual stresses induced by manufacturing. These residual stresses can be relaxed or redistributed by thermal loading. The presence of internal stress influences the dynamic response of parts, and this is of particular interest in thin plates subject to thermoacoustic loading in hypersonic vehicles and fusion reactors.
To measure the changes in shape and modal frequencies caused by thermal loading of geometrically-reinforced thin plates that were additively manufactured in Inconel 625.
Plates were additively-manufactured in landscape and portrait orientations using laser powder bed fusion. The plates were heated to a nominal temperature of 820 °C, which was expected to alleviate the residual stress from the build process. Pre- and post-heating, their modal frequencies were found experimentally and pulsed-laser stereo (3D) digital image correlation was used to evaluate their modal shapes. The resultant modal frequencies and shapes were compared with those from a subtractively-manufactured plate.
It was found that the heat cycle changed the shape of the plates relative to their as-manufactured state in addition to changing their natural frequencies and modal shapes.
The change in shape induced by heating caused shifts in the natural frequencies and changes in the corresponding modal shapes. The results show quantitatively for the first time the important role that residual stresses can play in the dynamic response of geometrically-reinforced thin plates manufactured by additive and subtractive processes.
The online version contains supplementary material available at 10.1007/s11340-024-01130-5.
增材制造的零件包含制造过程中产生的残余应力。这些残余应力可通过热加载得以松弛或重新分布。内应力的存在会影响零件的动态响应，这在高超音速飞行器和聚变反应堆中承受热声载荷的薄板中尤为重要。
测量由因科镍合金625增材制造的几何增强薄板热加载引起的形状和模态频率变化。
使用激光粉末床熔融工艺以横向和纵向取向增材制造薄板。将薄板加热到820℃的标称温度，预期这会减轻制造过程产生的残余应力。在加热前后，通过实验确定其模态频率，并使用脉冲激光立体（3D）数字图像相关技术评估其模态形状。将所得的模态频率和形状与减材制造的薄板的进行比较。
发现热循环除了改变薄板的固有频率和模态形状外，还使其相对于制造状态的形状发生了变化。
加热引起的形状变化导致固有频率发生偏移以及相应模态形状发生改变。结果首次定量显示了残余应力在通过增材和减材工艺制造的几何增强薄板的动态响应中所起的重要作用。
网络版包含可在10.1007/s11340-024-01130-5获取的补充材料。
