Abstract:

Because the multi-axial simultaneous vibration cannot be simply equivalent to single-axis sequential vibration, a load spectrum tailoring method is proposed to maintain the equivalence of the random vibration stress of triaxial vibration and single-axis vibration in the key parts of the structure. A method of root mean square value clipping of triaxial load spectrum is proposed by deducing the transformation relation between triaxial random vibration load and the response of key points of the structure. And based on the presupposition that the ratio of the equivalent stress of the key parts of the specimen under triaxial loads to the maximum equivalent stress under uniaxial loads should be equal to the ratio of the root mean square value of the stress response of the point before tailoring to that after tailoring, then considering the importance of different parts and the strength of materials, triaxial load spectrum root-mean-square value clipping criteria are defined. In order to avoid the uncertainty of the test caused by the diversity of spectral pattern tailoring, the pattern-preserving tailoring rules of the triaxial load spectrum are formulated. Finally, the effectiveness of the triaxial load spectrum tailoring method is verified by taking a typical cabin circuit board as an example. The triaxial load spectrum obtained by this method can not only avoid the over-test or under-test of important parts of the structure, but also ensure the equivalence of stress of key points and the certainty of the cut spectrum type.

Key words: random vibration, key point, stress equivalent, load spectrum tailoring