Lukoševičienė Ona, Leonavičius Mindaugas, Lukoševičius Vaidas, Bazaras Žilvinas
Department of Applied Mechanics, Faculty of Civil Engineering, Vilnius Gediminas Technical University, 10223 Vilnius, Lithuania.
Department of Transport Engineering, Faculty of Mechanical Engineering and Design, Kaunas University of Technology, 44249 Kaunas, Lithuania.
Materials (Basel). 2025 Jan 13;18(2):321. doi: 10.3390/ma18020321.
Cyclic failure problems in layered ductile iron are evident in a wide range of elements in transportation and mining equipment and depend on production technology and operating conditions. The aim of this study was to analyze the effect of residual stresses on the behavior of cyclic and static failure. The stress intensity factor, crack initiation, propagation patterns, static tension diagrams, and fracture behavior of compact tension (CT) specimens were determined. The samples used in this study were made from base cast iron, some of which were subjected to a special localized heat treatment. Experimental and analytical methods were used to conduct this study. The experiments were performed using original testing methods that adhered to the American Society for Testing and Materials (ASTM) regulations. The deformations of the partially heat-treated specimens due to residual stresses were determined using the grid method. The limiting stress intensity coefficient and the failure threshold under cyclic loading were determined in accordance with ASTM recommendations for various crack depths and openings. The results show that the heat treatment process readily produces residual stresses of different magnitudes, stress redistribution, different structures, and layer positions. Residual stresses affect the crack initiation and propagation. The stress intensity factor depends on the depth of the crack, the position of the layers, and the magnitude of the residual stresses.
层状球墨铸铁中的循环失效问题在运输和采矿设备的多种部件中都很明显，并且取决于生产工艺和运行条件。本研究的目的是分析残余应力对循环和静态失效行为的影响。测定了紧凑拉伸（CT）试样的应力强度因子、裂纹萌生、扩展模式、静态拉伸图和断裂行为。本研究中使用的样品由基体铸铁制成，其中一些经过了特殊的局部热处理。采用实验和分析方法进行本研究。实验采用符合美国材料与试验协会（ASTM）规定的原始测试方法进行。使用网格法测定了部分热处理试样由于残余应力产生的变形。根据ASTM对各种裂纹深度和开口的建议，确定了循环加载下的极限应力强度系数和失效阈值。结果表明，热处理过程容易产生不同大小的残余应力、应力重新分布、不同的组织和层位置。残余应力影响裂纹的萌生和扩展。应力强度因子取决于裂纹深度、层的位置和残余应力的大小。
