A simplified random vibration analysis on portable electronic products

A random vibration analysis on a portable electronic product is presented in this paper based on a simplified physical model. The analysis emphasizes the dynamic relative transverse deflection, or the stopping distance, of the liquid crystal display, which is taken to be a thin elastic plate element, under random acceleration excitations. The expressions of the mean value and the autocorrelation function of the relative transverse deflection of the plate element are derived for stationary stochastic process acceleration excitations, and some statistical quantities are discussed. As a numerical example, a portable computer product under an idealized white noise stationary random acceleration excitation is analyzed, and some numerical results of the statistical quantities, such as the autocorrelation function and the standard deviation, are presented. According to our analysis, to decrease the random dispersion of the relative transverse deflection (stopping distance) of the plate element, both the viscous damping coefficients of the plate and its support should be over designed, but with that of the plate being larger than that of the support. In practice, it is possible to select proper support materials and correctly design the mounting of the chassis to meet this requirement, because compared to the liquid crystal display, the mounting of the chassis is easier to design for. With a normal distribution assumption for the relative transverse deflection, the maximum possible relative transverse deflections (stopping distances) of the plate element are obtained, at chosen confidence levels, which can be used as a preliminary check for designing a similar portable computer product.