Abstract
The robustness and stability of the system depend on structural integrity. This stability is, however, compromised by aging, wear and tear, overloads, and environmental factors. A study of vibration and fatigue cracking for structural health monitoring is one of the core research areas in recent times. In this paper, the structural dynamics and fatigue crack propagation behavior when subjected to thermal and mechanical loads were studied. It investigates the modal parameters of uncracked and various cracked specimens under uniform and non-uniform temperature conditions. The analytical model was validated by experimental and numerical approaches. The analysis was evaluated by considering different heating rates to attain the required temperatures. The heating rates were controlled by a proportional-integral-derivative (PID) temperature controller. It showed that a slow heating rate required an ample amount of time but more accurate results than quick heating. This suggested that the heating rate can cause variation in the structural response, especially at elevated temperatures. A small variation in modal parameters was also observed when the applied uniform temperatures were changed to non-uniform temperatures. This study substantiates the fatigue crack propagation behavior of pre-seeded cracks. The results show that propagated cracking depends on applied temperatures and associated mass. The appearance of double crack fronts and multiple cracks were observed. The appearance of multiple cracks seems to be due to the selection of the pre-seeded crack shape. Hence, the real cracks and pre-seeded cracks are distinct and need careful consideration in fatigue crack propagation analysis.
Highlights
Engineering structures and components experience fatigue and failure during operations
The model was built in a fixedwere tested for various temperatures in the dynamic mechanical analyzer (DMA) and free boundary condition
The sinusoidal loadmacro-expansion with an amplitude probe of 2 mm wasused enforced as thermal-mechanical analyzer (TMA)
Summary
Engineering structures and components experience fatigue and failure during operations. This failure is due to many reasons, such as wear and tear, cycles of loads, working environments, crack occurrence and propagation, etc. This paper aims to study the modal and crack propagation behavior of a beam subjected to thermal and mechanical loads. Vibration-based studies examined the dynamic response of beams and damage quantification approaches for metallic and non-metallic materials [11,12,13,14]. Techniques were developed to predict the high-frequency response of beams, explore the natural thermal vibration, and study the mechanical fatigue of metallic beams. The researchers noticed that the applied thermal load generates thermal stresses and changes in mechanical properties. Recent review papers on the dynamic response of the system at elevated temperatures can be found in the literature [1,2,30,31,32,33]
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