Thermoplastic Cavity Reinforcement Insert for Automotive Sealing
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Solution Overview
Problem
Existing structural reinforcement materials face challenges such as inadequate sealing, uneven expansion, sensitivity to heating processes, and increased production costs due to the need for multiple shapes and sizes, which affect the strength and vibration transmission in hollow cavities of products like automobile bodies.
Innovation Solution
A structural reinforcement system using a carrier with a thermoset or thermoplastic material that transforms from a solid or dough phase to a liquid phase upon heating, flowing into cavities and adhering to provide structural reinforcement, with optional use of structural foam to prevent flow into certain regions and adhesives for secure placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If expansible material is applied to a molded carrier, then structural reinforcement is achieved, but the material may not be securely joined to the carrier leading to uneven or inadequate sealing
Solution Approach 1:
The reinforcement system is divided into two functional segments: a carrier component that provides structural support and a separate expansible material that provides sealing. This segmentation allows each component to be optimized independently - the carrier for strength and the expansible material for conformal sealing contact.
Solution Approach 2:
The carrier is pre-formed with specific geometric features (such as recesses, flanges, or mounting surfaces) that prepare it for secure attachment of the expansible material before expansion occurs. This preliminary preparation ensures proper alignment and bonding surface area.
2Strength
If expansible material is used to reinforce hollow cavities, then strength is improved, but expansion may not reach every nook and cranny of an irregularly shaped carrier
Solution Approach 1:
The expansible material provides locally adaptive sealing by expanding to fill specific voids and conform to irregular surfaces. Different regions of the material can expand to different degrees based on local cavity geometry, ensuring complete contact in all areas including nooks and crannies.
Solution Approach 2:
The material undergoes a parameter change through thermal expansion, transitioning from a compact pre-formed state to an expanded state that fills irregular cavities. This parameter change (volume expansion) allows the material to adapt to complex geometries that would be impossible to achieve with rigid or pre-shaped components.
3Strength
If known expansible structural reinforcement materials are used, then reinforcement is achieved, but they are thick even before expansion requiring 8 to 10 mm thickness for e-coat flow and assembly tolerances
Solution Approach 1:
The carrier is designed as a thin-walled structure with strategic reinforcement features rather than a thick solid form. The carrier walls are optimized to provide necessary structural support while minimizing thickness, allowing the overall assembly to meet assembly tolerance requirements with reduced material usage.
Solution Approach 2:
The system combines two materials with complementary properties: a rigid carrier material (such as metal or rigid plastic) that provides structural strength in a thin profile, and an expansible sealing material that provides compliance and seal. This composite approach allows thin overall thickness while maintaining both strength and sealing capabilities.
4Weight of moving object
If hollow cavities are introduced to reduce weight, then overall weight is reduced, but the strength or energy-absorbing characteristics of structural members are reduced
Solution Approach 1:
The carrier is designed with non-uniform thickness and strategic reinforcement features located at high-stress areas. The carrier walls are thin in low-stress regions to minimize weight but thicker or reinforced at critical locations to maintain structural strength, achieving optimal weight-strength ratio.
Solution Approach 2:
The combination of rigid carrier and expansible material creates a composite structure where the rigid carrier provides primary structural support and the expansible material provides secondary reinforcement and energy absorption. This composite approach maintains strength while keeping overall weight lower than solid structures.
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 system achieves robust structural reinforcement with reduced thickness, improved global system performance, and independence from heating conditions, while maintaining strength and sealing effectiveness across various cavity shapes and sizes.
Implementation Method 1
a thermoset or thermoplastic material which transforms from a solid or dough phase to a liquid phase upon heating
Implementation Method 2
transforms from a solid or dough phase to a liquid phase upon heating
Implementation Method 3
structural foam to prevent flow of the reinforcement material into certain regions of the cavity
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A structural reinforcement material (20) is provided that includes a base material selected fr om the group consisting of thermosets, low viscosity thermoplastics with short transition phas es and low viscosities, low melting point metallic alloys, and combinations thereof. At STP, the structural reinforcement material (20) is a solid or a formable dough or a mixture thereof. When heated to an activation temperat ure, the structural reinforcement material (20) becomes flowable into a cavity (10). Following cooling, the structural reinforcement material (20) is a solid or a thermoset with a strength sufficient to reinforce the cavity (10). A structural reinforcement insert (111) comprising the structural reinforcement ma terial (20) is also provided, as is a reinforced cavity (10) of an automobile (2) and a method of reinforcing a cavity (10).