방충재의 동적 성능평가를 위한 압축속도 및 각도를 독립변수로 한 압축성능시험과 접안에너지 결정계수 제안

Proposal of Correction Factors of Berthing Energy Based on Compression Performance Tests with Velocity and Angle as Independent Variables

This study aims to develop correction factors that reflect the dynamic berthing environment of actual vessels, thereby enhancing the accuracy of berthing energy estimation and the selection of rubber fenders in port facilities. Conventional fender performance evaluations rely primarily on standardized vertical compression tests under controlled laboratory conditions. However, such methods do not sufficiently capture the real berthing environment, where variables such as approach angle, hull flare, and velocity variations significantly influence the behavior of marine fenders. Recognizing this gap, the present research establishes a dedicated testing framework that allows independent variation of compression angle and compression velocity, enabling the derivation of angular factors (AF) and velocity factors (VF) that more realistically account for operational conditions. To achieve this, scaled-down cone-type fenders produced domestically were tested using a dynamic universal testing machine with custom-designed fixtures, ensuring accurate measurement under both vertical and inclined compression. The results confirmed that increasing compression angle leads to reduced energy absorption and reaction force, while increasing compression velocity enhances these values due to the viscoelastic nature of rubber. Derived AFs and VFs were compared against correction factors provided by major domestic and international fender manufacturers. While international data showed good agreement with the experimental outcomes, notable discrepancies were observed in some domestic datasets, suggesting potential underestimation of design forces. Furthermore, the study applied the proposed correction factors to existing design cases from large domestic ports. The comparison revealed that neglecting dynamic corrections, particularly velocity effects, can lead to significant underestimation of reaction forces up to 24% which may compromise the safety of structures. These findings highlight the necessity of incorporating dynamic correction factors into design practice. In conclusion, this research not only provides validated AF and VF values for cone-type fenders but also establishes a test methodology for future studies. Adoption of these correction factors is expected to improve the reliability, safety, and cost-effectiveness of berth design, while pointing to the need for further studies on temperature factors and diverse fender types.