METHOD TO SPECIFY RANDOM VIBRATION TESTS FOR PRODUCT DURABILITY VALIDATION

摘要

PURPOSE: A method is provided for determining the testing profile for accelerated laboratory random vibrational testing of a product. CONSTITUTION: A method include the steps of (i) selecting the frequency range covered in the laboratory accelerated testing, (ii) developing a simplified composite Power Spectral Density function PSDj(f) including scaling coefficients representative of the PSD for random vibration loadings in expected field vibrations levels, (iii) developing the shape of an accelerated laboratory test Power Spectral Density of PSDT(f) for producing on the product the test acceleration forces corresponding to the PSDj function, (iv) calculating the stress response curve H(f) for the product representative of the transmissibility function from the input acceleration forces to the local vibration stress forces, (v) selecting the test duration T, and then calculating the amplification factor AF from the relationship(a), (vi) recalculating the accelerated PSD profile, PSDT(f) for testing based on the selected test duration and the amplification factor (b), and then (vii) testing the product using the selected PSD function, to validate the required performance lifetime for the product when no test failures are observed over test duration T.