Reinforcing Insert With Through Orifices for Plastic Bodywork
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Solution Overview
Problem
The mechanical reinforcement of plastic bodywork parts, such as tailgates, with molded inserts faces issues due to differences in expansion coefficients between the plastic and metal inserts, leading to stress-induced brittleness and potential cracking from thermal and mechanical forces.
Innovation Solution
A reinforcing element with through orifices, or notches, that provide additional deformation ability and increased interface length at the edge between the insert and the plastic part, reducing stress and promoting coupling, while blind orifices contribute to mechanical cohesion without emerging at the contour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the edge overmolding is increased to address stress from thermal expansion differences, then the stress resistance is improved, but the mass of the assembly increases
Solution Approach 1:
The reinforcing insert incorporates through orifices (holes) that allow the plastic material to pass through and mechanically interlock with the insert. This creates a porous-like structure that enhances the interface between the plastic and metal, improving stress resistance and preventing cracking without requiring increased overmolding thickness or mass.
2Strength
If a stronger plastic is used to prevent cracking from thermal stresses, then the strength is improved, but the mass of the assembly increases
Solution Approach 1:
The through orifices in the reinforcing insert create mechanical interlocking points where the plastic material passes through and anchors to the insert. This structural modification enhances the interface strength and crack resistance without requiring the use of stronger (and heavier) plastic material.
3Strength
If the interface length at the edge between the insert and overmolding is increased to promote coupling, then the mechanical coupling is improved, but the device complexity increases
Solution Approach 1:
The reinforcing insert is segmented with multiple through orifices distributed across its surface. This segmentation creates multiple discrete mechanical interlocking points between the plastic and the insert, enhancing the overall interface strength and coupling without requiring a single complex continuous structure.
Solution Approach 2:
The through orifices create a porous-like structure in the insert that allows the plastic material to penetrate and mechanically interlock. This simple hole-based approach increases the effective interface length and coupling strength without adding significant structural complexity to the insert design.
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 design effectively relaxes stresses between the insert and the bodywork part, enhancing the mechanical coupling and reducing the likelihood of cracking, without increasing the assembly's mass by using a stronger plastic or thicker overmolding.
Implementation Method 1
the plastic material passes from one face of the insert to the other, bypassing and covering the part edge
Implementation Method 2
the bodywork part and the insert exhibit differences in expansion under the effect of temperature, due to the fact that the part and the insert are made of materials having a different CLTE
Data Source
AI summary
A reinforcing element for a bodywork part made from plastic, forming an insert capable of being at least partially overmolded in the bodywork part, the reinforcing element including a wall delimited by a contour, the wall including an orifice that passes all the way through the thickness of the wall of the reinforcing element, which orifice is a notch emerging at the contour, or a blind orifice at the contour, located, at least in part, in an area of the contour that extends over 40 mm in width from the wall.