An empirical model integrating dimensional analysis and Box-Behnken design for crack detection in rotor fan blades

Abstract

Due to continuous operations and manufacturing errors, fatigue cracks can emerge after hours of service; this causes a fan blade failure and potentially ruins an entire engine, turbo machinery, or rotating machinery of a similar kind. This paper focuses on the condition monitoring of the fan blade for detecting cracks occurring in these blades by analyzing the vibration responses. The mathematical formulation is carried out using the matrix method of dimensional analysis, which is dependent on the fundamental quantities of force, Length, Time, and Temperature (FLTƟ) systems of units. Numerical analysis in ANSYS software is done to comprehend the blade harmonic response for the cracked blade condition. Experimentation is also carried out on Tiera fault simulation machinery equipment, where vibration responses are measured and analyzed for crack detection in the blades. The tests were performed for three different cracks of different lengths and analyzed by varying parameters such as load speed, for which experiments are planned using a Box-Behnken design method. The test results were confirmed with the model equations developed, and notable similarities were seen between the analytical, numerical, and experimental analyses. Thus, the proposed study will help detect the cracks in the blades, thus reducing the serious accidents or failure of the machinery.

Keywords

• fan blades
• crack detection
• dimensional analysis
• blade health monitoring