An automotive body joining position optimization analysis method of performing optimization analysis for determining optimal arrangement of a weld line to achieve one of:
- improving stiffness of an automotive body model;
- improving a fatigue life near the weld line for bonding and joining a parts assembly in the automotive body model;
- and minimizing a length of the weld line for all or a part of the automotive body model having a plurality of part models including a beam element, a two-dimensional element, and/or a three-dimensional element and having an initial weld line for bonding and joining the plurality of part models as the parts assembly, the method being executed by a computer and comprising:
- an analysis object model setting step of setting all or a part of the automotive body model as an analysis object model;
- an optimization analysis model generating step of generating an optimization analysis model in which all candidates for weld line serving as candidates for weld lines in the optimal arrangement are set to the analysis object model;
- a variable amplitude load condition setting step of setting a variable amplitude load condition in which a variable amplitude load to be given to the optimization analysis model is divided into loading conditions of a plurality of different vibration patterns and a predetermined cycle number of loading conditions of the vibration patterns are combined to form one sequence;
- a target fatigue life setting step of setting a target fatigue life of the optimization analysis model by a number of sequences of the variable amplitude load condition;
- an optimization analysis condition setting step of, in order to perform optimization analysis in which the optimization analysis model is set as a target of optimization,
- determining a number of cycles to fracture near each of the candidates for weld line for each of the loading conditions of the vibration patterns,
- determining a sum of ratios between the cycle number of the loading conditions of the vibration patterns and the number of cycles to fracture by the number of sequences of the variable amplitude load condition set by the target fatigue life setting unit as a liner cumulative damage of each of the candidates for weld line, and
- setting a condition regarding the liner cumulative damage of each of the candidates for weld line, which are to be left by optimization analysis, a condition regarding stiffness of the optimization analysis model, and a condition regarding a length of each of the candidates for weld line, which are to be left by optimization analysis, as an objective or a constraint, which is an optimization analysis condition;
- and
- an optimization analysis step of
- giving the variable amplitude load condition set by the variable amplitude load condition setting unit to the optimization analysis model,
- performing optimization analysis under the optimization analysis condition, and
- determining arrangement of each of the candidates for weld line as optimal arrangement of the weld line to achieve one of:
- reducing the liner cumulative damage of each of the candidates for weld line;
- improving stiffness of the optimization analysis model;
- and minimizing a length of each of the candidates for weld line, which are to be left.