Stiffener Design to Maintain Line Heating Efficiency during the Lifting Process Considering Phase Transformation.

Area of Science:

• Materials Science
• Mechanical Engineering
• Naval Architecture

Background:

• Welding is primary for steel structures in shipbuilding.
• Post-welding lifting can negate line heating correction effects, delaying assembly.
• Reheating after lifting is inefficient and time-consuming.

Purpose of the Study:

• To propose a design method for permanent stiffeners.
• To prevent the loss of line heating effects during lifting processes.
• To optimize stiffener design for sustained line heating efficiency.

Main Methods:

• Calculated physical property changes from line heating using inherent strain theory.
• Determined limiting stress for line heating effect disappearance.
• Modeled ship block local areas with stiffeners using square plate theory and superposition.
• Analyzed stiffener stress and distance effects on a local model.
• Utilized finite element analysis (FEA) for validation.

Main Results:

• Quantified the limiting stress for line heating effect loss.
• Identified optimal stiffener configurations (shape, spacing) based on stress analysis.
• FEA confirmed the designed stiffener's effectiveness in maintaining line heating benefits.

Conclusions:

• The proposed stiffener design effectively preserves line heating effects through lifting processes.
• This method significantly improves efficiency in ship assembly by avoiding reheating.
• Optimized stiffener installation is crucial for maintaining structural integrity and assembly timelines.