Finite element analysis of a trawling winch frame
Amenzou, Ismail (2026)
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-202604237623
https://urn.fi/URN:NBN:fi:amk-202604237623
Tiivistelmä
This thesis presents a static structural finite element analysis of a full-scale trawling winch frame manufactured by a Moroccan fishing equipment company. The study was motivated by observations during an intern-ship where a decommissioned single-drum hydraulic-driven trawling winch exhibited visible signs of structural degradation, giving rise to the idea of investigating its structural behavior.
The CAD geometry of the frame was developed in SolidWorks 2025, based on field measurements of the physical winch. The FEA model was constructed in ANSYS Mechanical 2024 R2 using a mixed-element approach, comprising shell bodies for the steel plates, beam elements for the HSS beams and bolted connections, and 3D solid elements for the hubs, torque-transmitting keys, and gussets. Contact interfaces were modeled using frictionless, frictional, and bonded Multi-Point Constraint formulations to capture the realistic load transfer behavior of the welded, bolted, and key-keyway connections. The operational load case was derived from the ‘ISO 6115:1988 Shipbuilding – Trawl Winches’ standard, applying a minimum drum line pull of 160 kN at half rope length, corresponding to a Type B trawl winch of 12 tonnes nominal capacity.
The results show that the frame exhibits a maximum total deformation of 0.44 mm, confirming a structurally rigid behavior under the applied loading. The highest equivalent Von-Mises stress of 266.9 MPa occurs at the corner junction between the back plate and base plate on the motor side, identified as a stress singularity through a mesh convergence study and excluded from the structural assessment. The surrounding con-verged stresses remain close to the material yield strength. The torque-transmitting keys exhibit peak Von-Mises stresses of 162 MPa and 142 MPa for the upper and lower keys respectively, with maximum shear stresses of 86.8 MPa and 81.4 MPa, and contact pressures of approximately 181 MPa distributed uniformly across their loaded flanks. Bolt utilization factors were calculated according to EN 1993-1-8, with maximum values of 0.12 for the M20 bolts and 0.18 for the M24 bolts.
The analysis confirms that the winch frame possesses adequate structural integrity under the ISO 6115:1988 minimum line pull condition, with the back plate to base plate junction identified as the most critical structural region, warranting attention in any future design modification or fatigue assessment.
The CAD geometry of the frame was developed in SolidWorks 2025, based on field measurements of the physical winch. The FEA model was constructed in ANSYS Mechanical 2024 R2 using a mixed-element approach, comprising shell bodies for the steel plates, beam elements for the HSS beams and bolted connections, and 3D solid elements for the hubs, torque-transmitting keys, and gussets. Contact interfaces were modeled using frictionless, frictional, and bonded Multi-Point Constraint formulations to capture the realistic load transfer behavior of the welded, bolted, and key-keyway connections. The operational load case was derived from the ‘ISO 6115:1988 Shipbuilding – Trawl Winches’ standard, applying a minimum drum line pull of 160 kN at half rope length, corresponding to a Type B trawl winch of 12 tonnes nominal capacity.
The results show that the frame exhibits a maximum total deformation of 0.44 mm, confirming a structurally rigid behavior under the applied loading. The highest equivalent Von-Mises stress of 266.9 MPa occurs at the corner junction between the back plate and base plate on the motor side, identified as a stress singularity through a mesh convergence study and excluded from the structural assessment. The surrounding con-verged stresses remain close to the material yield strength. The torque-transmitting keys exhibit peak Von-Mises stresses of 162 MPa and 142 MPa for the upper and lower keys respectively, with maximum shear stresses of 86.8 MPa and 81.4 MPa, and contact pressures of approximately 181 MPa distributed uniformly across their loaded flanks. Bolt utilization factors were calculated according to EN 1993-1-8, with maximum values of 0.12 for the M20 bolts and 0.18 for the M24 bolts.
The analysis confirms that the winch frame possesses adequate structural integrity under the ISO 6115:1988 minimum line pull condition, with the back plate to base plate junction identified as the most critical structural region, warranting attention in any future design modification or fatigue assessment.