Resin Door Inner Panel Fragile Portions Impact Deformation
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Solution Overview
Problem
Vehicular door inner panels made of resin tend to undergo significant deformation and cracking during side-impact collisions, leading to unwanted protrusion towards the interior, which existing technologies fail to adequately mitigate.
Innovation Solution
Incorporating linear or dotted line-shaped fragile portions on the door inner panel, combined with high rigidity portions such as ribs and thickened areas, to concentrate stress and control deformation, thereby limiting the extent of deformation towards the interior member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the door inner panel is made of resin to reduce weight, then weight is reduced, but deformation resistance under impact load deteriorates
Solution Approach 1:
The door inner panel is segmented into multiple regions by providing fragile portions (notches) that divide the panel into multiple segments. These segments can deform independently under impact load, distributing the stress and preventing catastrophic failure while maintaining overall structural integrity
Solution Approach 2:
The panel is designed with non-uniform local properties: fragile portions (notches) are strategically placed in specific regions to control deformation patterns, while other regions maintain full thickness for strength. This creates zones with different mechanical properties optimized for their specific functions
2Strength
If the door inner panel thickness is increased to improve strength, then deformation resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The fragile portions (notches) are pre-formed during the molding process itself, rather than requiring post-manufacturing operations. The molding cavity includes features that directly create the notches and varied thickness regions, integrating the strengthening features into the base manufacturing process
Solution Approach 2:
The panel thickness parameter is varied locally throughout the structure. Instead of uniform thickness, the panel has regions of different thickness (full thickness in some areas, reduced thickness at fragile portions), optimizing strength where needed while reducing material usage elsewhere
3Stability of the object's composition
If fragile portions are provided in the door inner panel to control deformation, then deformation control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The fragile portions are pre-formed as integral features of the molding process. The mold cavity includes built-in features that automatically create the notches and varied thickness regions during standard molding operations, eliminating the need for separate precision machining or post-processing steps
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
The solution effectively reduces the amount of deformation of the door inner panel towards the interior member by concentrating stress in fragile areas and increasing rigidity between them, allowing for stable bending and absorption of impact loads, thus preventing excessive protrusion and enhancing safety.
Implementation Method 1
stress is concentrated in the fragile portions, and the door inner panel bends and deforms toward the vehicle interior, using the fragile portions as starting points of bending deformation
Implementation Method 2
the door inner panel is deformed when an impact load is applied to the door inner panel
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A vehicular door structure includes a door outer panel (14) that constitutes a door exterior panel; a door inner panel (16) that constitutes a door interior panel and is made of a resin, the door inner panel having a first side that is provided to the door outer panel; and a door interior member located on a second side of the door inner panel, the door interior member facing to the vehicle interior, wherein the door inner panel includes a panel part (16P) that has a plurality fragile portions (24), the fragile portions having a linear shape or a dotted line shape and being provided in parallel with each other while being spaced from each other in at least one direction of a door width direction and a door vertical direction.