This paper investigates the interdependencies of crack depth and crack location on the dynamic response of a cantilever beam under thermo-mechanical loads. Temperature can influence the stiffness of the structure, thus, the change in stiffness can lead to variation in frequency, damping and amplitude response. These variations are used as key parameters to quantify damage of Aluminum 2024 specimen under thermo-mechanical loads. Experiments are performed on cantilever beams at non-heating (room temperature) and elevated temperature, i.e., 50°C, 100°C, 150°C and 200°C. This study considers a cantilever beam having various initially seeded crack depth and locations. The analytical, numerical and experimental results for all configurations are found in good agreement. Dynamic response formulation is presented experimentally on beam for the first time under thermo-mechanical loads. Using available experimental data, a novel tool is formulated for in-situ damage assessment in the metallic structures. This tool can quantify and locate damage using the dynamic response and temperature including the diagnosis of subsurface cracking. The obtained results demonstrate the possibility to diagnose the crack growth at any instant within the operational condition under thermo-mechanical loads.
In this paper, a methodology is proposed which can be used to predict the crack growth and fatigue life of a cantilever beam made of Acrylonitrile Butadiene Styrene (ABS) manufactured with fused deposition modeling Three beam configurations based on length (L=110 mm, L =130 mm, and L=150 mm) are considered. Empirical relationships are formulated between the natural frequency and the crack growth. The analytical and experimental results are found in good agreement for all configurations. Using the experimental data, global relation is formulated for the crack depth prediction. This global relation is useful for an in-situ crack depth prediction with an error of less than10%. Later a residual fatigue life of these specimens is compared with metallic structure (Aluminum 1050) of similar configuration available in the literature. It is found out that the ABS material has more residual fatigue life compared to the metallic structure at the same frequency drop. Based on remaining fatigue life, ABS material can be a potential material to manufacture machine components under cyclic loads.
This article presents a literature review of published methods for damage identification and prediction in mechanical structures. It discusses ways which can identify and predict structural damage from dynamic response parameters such as natural frequencies, mode shapes, and vibration amplitudes. There are many structural applications in which dynamic loads are coupled with thermal loads. Hence, a review on those methods, which have discussed structural damage under coupled loads, is also presented. Structural health monitoring with other techniques such as elastic wave propagation, wavelet transform, modal parameter, and artificial intelligence are also discussed. The published research is critically analyzed and the role of dynamic response parameters in structural health monitoring is discussed. The conclusion highlights the research gaps and future research direction.
This paper investigates the interdependencies of a cantilever beam modal behavior, its dynamic response and crack growth. A methodology is proposed which can predict the crack growth in a metallic beam by using its dynamic response only. Analytical and numerical relationships are formulated in between the fundamental mode and the crack growth by using the existing literature and finite element analysis (FEA) software respectively. Relationship in between the dynamic response and modal behavior is formulated empirically. All three relationships are further used to predict crack growth and propagation. The load conditions are considered same in all the experiments for model development as well as for the model validation. Predicted crack growth is
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