Spot-Weld Break Prediction with Element-Size-Adjusted Moment Limits
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Solution Overview
Problem
Current break prediction methods for spot-welded portions in vehicle collision analysis, particularly using finite element methods, face challenges in achieving accurate predictions due to dependence on element size, especially when moments are applied, leading to inconsistent results and low accuracy for ultra-high-tensile materials and varying deformation conditions.
Innovation Solution
A break prediction method that calculates a break limit moment using a function incorporating element size as a variable, allowing for accurate discernment of joint portion failures by determining whether applied moments exceed this limit, thereby stabilizing prediction accuracy regardless of element size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional break prediction methods based on shear joint type or cross joint type tensile test are used, then prediction can be performed for simple loading conditions, but prediction accuracy is insufficient for complex deformation states including moment loading in actual vehicle collision
Solution Approach 1:
The invention introduces a moment coefficient as a new parameter to account for moment loading effects. By multiplying the break limit moment by this coefficient (which depends on element size and material properties), the method adapts to complex deformation states while maintaining prediction accuracy for both simple and complex loading conditions
2Adaptability or versatility
If finite element method is used for collision deformation analysis, then complex vehicle structures can be analyzed, but break prediction accuracy varies depending on element size of base material portion
Solution Approach 1:
The invention introduces a moment coefficient that explicitly depends on element size parameters. This coefficient compensates for the influence of element size on break prediction, allowing accurate results regardless of the mesh density used in the finite element model. The coefficient is calculated based on element size and material properties, thereby normalizing the prediction across different model resolutions
3Measurement precision
If element size is reduced to improve model accuracy, then collision deformation analysis precision improves, but break prediction becomes more sensitive to element size variations
Solution Approach 1:
The moment coefficient is specifically designed to counteract the sensitivity of break prediction to element size changes. By incorporating element size into the coefficient calculation, the method ensures that refined meshes do not artificially increase or decrease predicted break loads, thereby maintaining consistent and reliable break prediction across different levels of model refinement
Data Source
AI summary
A break prediction method according to the present invention predicts a break of a joint portion of an object to be analyzed including a pair of members joined to each other by using a finite element method, and includes a first step of acquiring at least an element size of a base material portion, from among parameters set in an element model for the object to be analyzed; a second step of calculating, as a break discernment standard, a break limit moment defined by a function including the element size of the base material portion as a variable; and a third step of discerning whether the moment applied to the joint portion in a deformation analysis of the element model for the object to be analyzed exceeds the break limit moment, and outputting the result of the discernment as a break prediction result for the joint portion.