Analysis and optimization of dynamic characteristics of the supporting frame structure of small fishing boat

The dynamic characteristics of the support frame structure are critical factors influencing the safety and stability of small fishing boat. A prestressed modal analysis model of the support frame was established using the finite element method to evaluate stress, deformation, natural frequency, and modal shapes under maximum bending load conditions. To validate the accuracy of the simulated natural frequencies, the support frame was freely suspended using wide elastic ropes, and a hammering test method was employed, achieving a maximum error of less than 7.5 %. Based on a multi-objective optimization approach, optimal designs with varying thicknesses were developed to minimize stress peaks and maximize natural frequencies without increasing mass. Combining the results from strength and modal analyses, structural improvements such as adding local reinforcing ribs were proposed. Modal simulations confirmed that the optimized design can effectively mitigate low-frequency vibrations and enhance structural reliability.