Rib Thickness Optimization of Vibration Test Fixture Based on Orthogonal Array for Weight Reduction

Vibration test fixtures are widely used to evaluate the dynamic characteristics of structures. However, their performance is often limited by their excessive weight and unintended resonances. Conventional optimization methods, such as genetic algorithms, have been applied to improve fixture design; however, they often require considerable computational effort and are inefficient for problems involving discrete design variables. To address these limitations, this study proposes a rib thickness optimization method based on an orthogonal array. The novelty of the proposed method lies in the introduction of an influence value that simultaneously reflects lightweighting effect and first natural frequency change. The proposed method generates orthogonal arrays for rib-thickness configurations, performs modal analyses, and applies analysis of means based on this influence value to identify ribs with low structural influence for thickness reduction. Its effectiveness was validated through comparison with a genetic algorithm under identical conditions. The results showed that the orthogonal array achieved rib reduction patterns similar to those of the genetic algorithm while requiring only 0.84% of the analyses and 1.14% of the computation time required by the genetic algorithm. These findings demonstrate that the orthogonal array provides an efficient and practical alternative for rib thickness optimization in vibration test fixtures.