Nonlinear response with snap-through and fatigue life prediction for panels to thermo-acoustic loadings

Abstract

Thin-walled structures under thermo-acoustic loadings exhibit a complex nonlinear response which results in high cycle fatigue failure. The aim of the present paper is to analyze the influences of thermal-acoustic excitations on nonlinear dynamics response, and then give the corresponding multi-axial fatigue life estimation. The nonlinear responses of a clamped aluminum plate (2024-T3) under different thermal-acoustic loadings are firstly obtained, which include the response of the plate in pre/post buckled conditions and in snap-through conditions. Then the statistical properties with different temperatures and sound pressure levels are analyzed for further research on nonlinear response dynamics. Based on the thermo-acoustic response obtained, the rain flow matrix scheme is used to determine the distribution of fatigue cycles. Then the Miner accumulative damage model is employed to predict high cycle fatigue life, combined with a non-zero mean stress model. Results show that the fatigue life of a pre-buckled plate decreases with the increase of temperature. For a post-buckled plate, as the temperature increases, the fatigue life of the plate undergoing persistent snap-through keeps decreasing to the lowest point, and then increases after entering an intermittent snap-through regime.

Active vibration control of functionally graded plates under random excitation

“…For SPL = 150 dB and uniformly elevated temperature (DT = 50 K), the uncontrolled random vibration is shown in Figure 11 In all these cases, the persistent-type snap-through motion occurs for uncontrolled and controlled vibrations. With increased control as seen in Figures 11 to 14, the number of high alternating amplitude cycles decreases, which may prolong the fatigue life of the FGM plate (Przekop et al, 2008;Sha et al, 2014).…”

Nonlinear random response and fatigue life estimation of curved panels to non-uniform temperature field and acoustic loadings

“…But the stress state for node 2, node 12, and node 14 will stay in compression all the time. Due to the damage caused by tensile loads is much bigger than that caused by compressive loads (Sha et al, 2012a), and the tensile mean stress associated with the nonlinear bending membrane coupling can significantly reduce the estimated fatigue life (Przekop et al, 2008), the tension stress will be taken as a conservative estimation of fatigue life. So the Root Mean Square (RMS) curves of the stress staying in tension are presented in Figure 11.…”

“…Random response of thin wall structures to combined thermo-acoustic loads are investigated using finite element method (Mei et al, 2000;Dhainaut et al, 2003;Przekop and Rizzi, 2007;Sha et al, 2012aSha et al, , 2012bSha et al, , 2013, the nonlinear snapthrough characteristics of thin wall structures to combined thermo-acoustic loads are pointed out. Random response and fatigue life of panels subjected to acoustic and thermal loads are also investigated using numerical simulation (Przekop et al, 2003;Radu et al, 2004;Yang, 2005;Sha et al, 2012aSha et al, , 2013. High temperature structural panels are usually connected with the cooler substructures that are regarded as heat sinks because of less temperature, even with uniform external heating, panels experience spatial temperature gradients because supporting substructures tend to act as heat sinks.…”

High Temperature Vibratory Response of Hastelloy-X: Stereo-DIC Measurements and Image Decomposition Analysis

“…However, in many of the high temperatures applications mentioned above (aero-engines, spacecraft re-entry, hypersonic flight) it is the coupled effects of thermal and mechanical loading, often at high frequencies, that provide an extreme operating environment which can critically affect structural performance and cause failure by the interaction of coupled, non-linear, failure modes that are otherwise not present [7]. Specifically, the combined high-temperature and vibration environment, as is experienced by aircraft during hypersonic flight and which is of interest to this study, is historically not well explored.…”