Variations in Structural Dynamic Characteristics Caused by Changes in Ambient Temperature: Ii. Analytical

Precise and detailed knowledge of the dynamic characteristics of structt~res has become increasingly important in recent years. As a consequence, the accuracy of experbnental data, which is often used to validate and update fmite element models, has become extremely i”lporta”t. It has been shown expetientally [II that small changes in ambient temperature can cause distinct variations in the natural frequencies of a lightly damped structure, which in turn may result in significant errors in expainxntal and analytical results. Therefore, a good understanding of the physical driving mechanisms involved is “ecessaly so that adequate stability control measures may be implemented. i This paper presents a” analytical investigation of the variations in natural frequency caused by small changes i” temperature. A” analytical plate dynamic model is developed accounting for the effects of temperature-dependent material properties. Changes in temperature influence Young’s modulus, stmctural dimensions (via thermal expansion), and boundary condition effects. These changes cause variations in the natural frequencies which result in marked changes in stmchlral dynamic response at frequencies near resonance, especially when damping is low. Natural frequencies decrease linearly with increasing temperature over the limited temperature range in this study. A sensitivity analysis indicates that the temperatare-dependence of Young’s modulus is the dominant factor influencing the variations in natural frequency, but boundary condition effects may also be irrpmtmt.