Temperature-Dependent Mastic Model for Automotive Panel Defect Prediction
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Solution Overview
Problem
Conventional methods for predicting appearance defects in automotive panel components due to thermal deformation, such as surface sink marks, are inaccurate due to oversimplification of the mastic model and failure to account for the actual binding state of the elastic adhesive, leading to delayed automotive development and incorrect buckling predictions.
Innovation Solution
A method involving finite element analysis (FEA) that models the joint structure of panel and reinforcing components with an elastic adhesive, using measured heating and cooling data to determine temperature-dependent elastic and thermal expansion coefficients, and incorporating thermal deformation parameters to simulate the behavior of panel components under temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a simplified mastic model is used in conventional FEA, then the analysis process is easier and faster, but the prediction accuracy of thermal deformation and appearance defects deteriorates
Solution Approach 1:
The patent applies parameter changes by making the elastic coefficient of the mastic temperature-dependent rather than using a constant value. The elastic coefficient varies according to the temperature change during heating and cooling processes, which accurately reflects the actual binding state of the mastic under thermal conditions. This resolves the contradiction by improving prediction accuracy through physically accurate parameter variation while maintaining FEA efficiency.
Solution Approach 2:
The patent introduces dynamic behavior of the mastic by allowing its elastic properties to change during the thermal process. Instead of a static material model, the mastic model dynamically adjusts its elastic coefficient based on temperature, capturing the time-dependent and temperature-dependent characteristics of the adhesive during heating and cooling cycles.
2Device complexity
If constant elastic coefficient is used for mastic, then the model is simpler and computation is faster, but the binding state representation becomes inaccurate leading to incorrect buckling predictions
Solution Approach 1:
The patent changes the elastic coefficient from a constant parameter to a temperature-dependent parameter. The elastic coefficient is determined to vary according to temperature changes during heating and cooling, which accurately represents the actual binding state of the mastic. This parameter change improves prediction reliability by capturing the true mechanical behavior under thermal conditions.
3Weight of moving object
If thinner panel components are used to reduce weight, then the automotive body weight is reduced, but the surface rigidity decreases making the panel more susceptible to thermal distortion
Solution Approach 1:
The patent addresses this contradiction by accurately modeling the temperature-dependent elastic properties of the mastic. The varying elastic coefficient captures the actual support provided by the adhesive under thermal conditions, allowing thinner panels to maintain sufficient surface rigidity through optimized adhesive bonding rather than increased panel thickness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for more accurate analysis of panel component behavior in the plate thickness direction, effectively predicting and evaluating the outer shape of automotive panel components, reducing the likelihood of thermal distortion defects without the need for actual prototypes.
Implementation Method 1
from actually measured heating and cooling data of the elastic adhesive, an elastic coefficient including change in elastic coefficient of the elastic adhesive in response to temperature change
Implementation Method 2
The mastic foams (expands) due to baking heat in the coating process of coating the automotive body and then hardens (shrinks) due to the subsequent cooling
Implementation Method 3
The panel component and the reinforcing component are connected (joined) together through an elastic adhesive called mastic
Data Source
AI summary
The behavior of a panel component in the plate thickness direction can be analyzed with greater accuracy. A joint structure in which a panel component and a reinforcing component facing together are connected through one or more elastic adhesives is modeled. A panel component behavior analysis method analyzes the behavior of the panel component by finite element analysis using a computer. From actually measured heating or cooling data of the elastic adhesive, an elastic coefficient including change in elastic coefficient of the elastic adhesive in response to temperature change and using temperature as a parameter is determined. The determined elastic coefficient using temperature as a parameter and a thermal expansion coefficient are set as physical property conditions of the elastic adhesive. The behavior of the panel component is analyzed in a temperature change condition in which a temperature change is applied to the joint structure in a previously-set temperature range.