Hussain Sajjad, Ghopa Wan Aizon W, Singh S S K, Azman Abdul Hadi, Abdullah Shahrum, Harun Zambri, Hishamuddin Hawa
Department of Mechanical and Manufacturing Engineering, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia.
Materials (Basel). 2022 Jul 14;15(14):4888. doi: 10.3390/ma15144888.
Vibration fatigue characteristics are critical for rotating machinery components such as turbine rotor blades. Lattice structures are gaining popularity in engineering applications due to their unique ability to reduce weight and improve the mechanical properties. This study is an experimental investigation of octet-truss lattice structure utilization in turbine rotor blades for weight reduction and to improve vibration fatigue characteristics. One completely solid and three lattice infilled blades with variable strut thickness were manufactured via additive manufacturing. Both free and forced experimental vibration analyses were performed on the blades to investigate their modal and vibration fatigue characteristics. The blades were subjected to random vibration using a vibration shaker. The response was measured using a triaxial accelerometer in terms of vibration acceleration time histories in the X, Y, and Z directions. Results indicate a weight reduction of up to 24.91% and enhancement in the first natural frequency of up to 5.29% were achieved using lattice infilled blades. The fatigue life of the blades was investigated using three frequency domain approaches, namely, Lalanne, Dirlik and narrow band. The fatigue life results indicate that the 0.25 mm lattice blade exhibits the highest fatigue life, while the solid blade exhibits the lowest fatigue life of all four blades. The fatigue life of the 0.25 mm lattice blade was 1822-, 1802-, and 1819- fold higher compared to that of the solid blade, using the Lalanne, Dirlik, and narrow-band approaches, respectively. These results can serve as the first step towards the utilization of lattice structures in turbine blades, with thermal analysis as the next step. Therefore, apart from being light weight, the octet-truss lattice infilled blades exhibited superior vibration fatigue characteristics to vibration loads, thereby making them a potential replacement for solid blades in turbine rotors.
振动疲劳特性对于涡轮转子叶片等旋转机械部件至关重要。晶格结构因其独特的减重和改善机械性能的能力而在工程应用中越来越受欢迎。本研究是一项关于在涡轮转子叶片中使用八面体桁架晶格结构以减轻重量并改善振动疲劳特性的实验研究。通过增材制造制造了一个完全实心的叶片和三个具有可变支柱厚度的晶格填充叶片。对叶片进行了自由和强迫实验振动分析，以研究它们的模态和振动疲劳特性。使用振动台对叶片施加随机振动。使用三轴加速度计在X、Y和Z方向上测量振动加速度时间历程的响应。结果表明，使用晶格填充叶片可实现高达24.91%的重量减轻和高达5.29%的第一固有频率提高。使用三种频域方法，即拉兰内法、迪利克法和窄带法，对叶片的疲劳寿命进行了研究。疲劳寿命结果表明，0.25毫米晶格叶片的疲劳寿命最高，而实心叶片在所有四个叶片中疲劳寿命最低。使用拉兰内法、迪利克法和窄带法时，0.25毫米晶格叶片的疲劳寿命分别比实心叶片高1822倍、1802倍和1819倍。这些结果可作为在涡轮叶片中使用晶格结构的第一步，下一步是进行热分析。因此，除了重量轻之外，八面体桁架晶格填充叶片在振动载荷下表现出卓越的振动疲劳特性，从而使其成为涡轮转子中实心叶片的潜在替代品。
