Numerical and Experimental Analysis of a Pre-Stressed Aluminum 6061-T6 Chassis for Offshore Structural Applications

Resumo

This paper presents an integrated experimental and numerical investigation of the tensile and modal behaviors of a pre-stressed aluminum chassis (Al 6061-T6) designed for offshore structural applications. The chassis, composed of four metallic parts assembled with a 0.15 mm interference fit, was subjected to a tensile test in which the base was fixed using bolted plates and the upper part was pulled via a gripping device. The experimental force–displacement curve revealed a maximum force of 486.6 N at 1.25 mm displacement. To complement the experimental results, a finite element analysis (FEA) was performed in ANSYS Workbench, employing a nonlinear contact model with friction. Simulations were conducted with friction coefficients of 0.15 and 0.3, and the best agreement with the experimental data was achieved for μ = 0.15, yielding a maximum force of 474.9 N at the same displacement. Modal analyses were carried out for two assembly conditions: bonded contact (no interference) and interference fit with μ = 0.15. The bonded model exhibited natural frequencies of 29.015 Hz, 117.47 Hz, 137.76 Hz, 142.81 Hz, 168.04 Hz, and 344.21 Hz, while the pre-stressed model showed significantly higher values: 72.543 Hz, 73.861 Hz, 83.645 Hz, 217.59 Hz, 264.61 Hz, and 267.74 Hz. These results demonstrate that pre-stressing through interference fit not only enhances the static load-bearing capacity but also increases the dynamic stiffness, shifting natural frequencies to higher values. The findings provide valuable insights for the design and reliability assessment of pre-stressed metallic components in offshore environments. This integrated approach, combining experimental validation and advanced numerical modeling, supports the development of safer and more efficient offshore structural systems, ensuring improved performance under demanding operational conditions.