Automobile Outer Panel Composite Structure for Thin-Sheet Stiffness
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Solution Overview
Problem
Thinning outer panels in automobiles to reduce weight leads to insufficient panel stiffness and potential surface strain due to differences in linear expansion coefficients, compromising both strength and appearance.
Innovation Solution
A panel structure featuring a thin outer panel with a resin member bonded using a room-temperature curing adhesive, where the resin member covers at least 50% of the inner surface and has a bending rigidity of 0.3×10^6 N·mm^2 or more, ensuring improved stiffness and appearance while maintaining weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the outer panel is thinned to reduce weight, then the weight of the automobile is reduced, but the panel stiffness becomes insufficient
Solution Approach 1:
The patent applies composite materials by combining a thin outer panel with a resin member to create a hybrid structure. The outer panel (0.3-0.5mm thick) is bonded to a resin member with specific bending rigidity (0.3×10^6 N·mm² or more), forming a composite assembly that achieves both weight reduction and sufficient panel stiffness. This composite approach allows the thin metal panel to maintain structural integrity through the added resin reinforcement.
Solution Approach 2:
The patent transitions from a single-layer thin panel to a multi-layer composite structure by adding the resin member in another dimension. This dimensional addition (creating a sandwich structure with adhesive layers) provides structural reinforcement without significantly increasing weight, as the resin member adds stiffness in the thickness direction while keeping individual layer thicknesses minimal.
2Weight of moving object
If the outer panel is thinned to reduce weight, then the weight of the automobile is reduced, but surface strain occurs due to difference in linear expansion coefficient
Solution Approach 1:
The patent introduces an adhesive portion as an intermediary layer between the outer panel and the resin member. This adhesive mediator (using room-temperature curing adhesive) bonds the two materials with different thermal expansion coefficients, accommodating the dimensional mismatch during bonding and subsequent temperature changes. The adhesive layer absorbs the stress from differential expansion, preventing surface strain and coating deterioration on the thin outer panel.
3Force
If high temperature heating is used to bond foam layer and outer sheet, then bonding strength is achieved, but surface strain occurs on thin outer sheet
Solution Approach 1:
The patent changes the bonding parameter from high-temperature heating to room-temperature curing. By using a room-temperature curing adhesive instead of thermal bonding processes, the bonding operation avoids subjecting the thin outer panel (0.3-0.5mm) to high temperatures that would cause differential thermal expansion and surface strain. The adhesive achieves sufficient bonding strength through chemical curing at ambient conditions rather than thermal bonding.
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 provides a lightweight, high-stiffness panel structure with improved external appearance by compensating for panel stiffness loss through strategic resin member placement and adhesive application, enhancing bending rigidity per unit weight.
Implementation Method 1
an adhesive portion that bonds the outer panel member and the resin member, wherein the adhesive portion contains a cured material of a room-temperature curing adhesive
Data Source
AI summary
This panel structure for an automobile (10) includes: an outer panel member (1) having a sheet shape; a resin member (2) that is disposed on an inner surface of the outer panel member (1); and an adhesive portion (3) that bonds the outer panel member (1) and the resin member (2), in which the outer panel member (1) includes a base metal (12) and a coating film (14) provided on the base metal (12), the base metal (12) has a sheet thickness of 0.3 mm to 0.5 mm, the resin member (2) has a bending rigidity of 0.3×106 N·mm2 or more, and the adhesive portion (3) contains a cured material of a room-temperature curing adhesive.