Automotive Body Weld Line Layout Under Variable-Amplitude Loads
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Solution Overview
Problem
Existing methods for determining weld line positions in automotive bodies fail to optimize both stiffness and fatigue life efficiently, particularly under variable amplitude loads, and are not applicable to chassis components or suspension parts joined by electric arc welding, leading to suboptimal designs and increased costs.
Innovation Solution
An optimization analysis method that uses a computer to analyze an automotive body model, setting weld line candidates, applying variable amplitude loading conditions, and performing sensitivity analysis to determine optimal weld line arrangements that minimize length, improve stiffness, and enhance fatigue life, while considering weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of continuous weld lines is increased to improve stiffness, then the fatigue life is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies mathematical optimization to determine the optimal number and arrangement of weld lines, transforming the qualitative decision into a quantitative parameter optimization problem. This resolves the contradiction by finding the precise parameter value (weld line arrangement) that achieves the desired stiffness while minimizing manufacturing cost.
Solution Approach 2:
The patent replaces trial-and-error mechanical testing and experience-based judgment with computer-aided engineering (CAE) analysis and mathematical optimization algorithms. This substitution enables precise determination of weld line configurations that optimize both stiffness and cost without repeated physical prototyping.
2Strength
If the number of continuous weld lines is increased to improve stiffness, then stress is suppressed, but the fatigue life is reduced due to local stress increase
Solution Approach 1:
The patent evaluates fatigue life at specific local positions near weld lines separately from overall stiffness considerations. By applying local quality assessment to the regions surrounding weld lines, the optimization can suppress overall stress while preventing local stress concentration that would reduce fatigue life.
Solution Approach 2:
The patent introduces CAE analysis as an intermediary evaluation tool that can predict both overall stiffness and local stress distribution before manufacturing. This intermediary analysis enables the optimization to simultaneously consider global structural performance and local fatigue-critical regions.
3Device complexity
If joining positions are determined by experience or intuition, then the process is simple, but the efficiency is poor and unnecessary weld lines are used
Solution Approach 1:
The patent replaces experience-based intuitive judgment with computer-aided engineering (CAE) analysis and mathematical optimization algorithms. This substitution transforms the weld line determination process from an art-based approach to a science-based quantitative optimization process, significantly improving design efficiency and eliminating unnecessary weld lines.
Solution Approach 2:
The optimization system performs self-evaluation by automatically analyzing multiple candidate weld line arrangements and selecting the optimal configuration based on predetermined objectives. This self-service capability eliminates the need for repeated trial-and-error testing and expert intervention.
4Strength
If joining positions are determined by stress analysis to increase the number of joining positions, then the stiffness is modified, but the local stress is increased and the design requires trial and error
Solution Approach 1:
The patent performs preliminary CAE analysis and mathematical optimization before finalizing the weld line arrangement. By conducting preliminary evaluation of multiple candidate configurations and their fatigue characteristics, the optimization determines the optimal arrangement in advance, avoiding the need for trial-and-error modifications during the design process.
Solution Approach 2:
The patent incorporates feedback from CAE analysis of fatigue life at weld line positions into the optimization process. The feedback mechanism allows the system to evaluate the impact of each candidate weld line arrangement on both stiffness and fatigue life, and adjust the configuration accordingly to avoid local stress concentration.
Data Source
AI summary
An optimization analysis method for joining positions of an automotive body, the method includes: setting a whole or a part of an automotive body model as an analysis object model; generating a weld line optimization analysis model; setting a variable amplitude loading condition; setting a target fatigue life of the weld line optimization analysis model; performing sensitivity analysis of a part model included in the weld line optimization analysis model, and selecting a low-stiffness-sensitivity part model having low sensitivity to the stiffness performance; generating a weld line and part shape optimization analysis model; setting optimization analysis conditions; and applying the variable amplitude loading condition to the weld line and part shape optimization analysis model, performing the optimization analysis, and obtaining an arrangement of candidates for weld lines and obtaining a remaining shape of the low-stiffness-sensitivity part model as an optimized shape of the part model.