Automobile Bonnet Flexibility via Zone-Segmented Inner Liner
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Solution Overview
Problem
The existing motor vehicle hood structure is rigid, leading to poor results in pedestrian impact tests, particularly for head impacts, due to the 'drum skin' effect, and requires additional material for wedging cords which are not aesthetically pleasing.
Innovation Solution
The bonnet structure is made more flexible in the front zone by eliminating wedging cords and extending the inner liner 6 mm or more from the outer skin beyond 50 mm from the front edge, with crimping around the periphery and additional attachment outside the front area, enhancing flexibility and reducing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wedging cords are used to connect the inner lining to the outer skin inside the periphery, then the connection strength is improved, but the rigidity increases causing the 'drum skin' effect that performs poorly in pedestrian impact tests
Solution Approach 1:
The bonnet is divided into two functional zones: a front zone (first predetermined zone) where no wedging cords are used to maintain flexibility for pedestrian safety, and a rear zone (second predetermined zone) where wedging cords are used to provide structural connection strength. This spatial segmentation resolves the contradiction by applying different connection strategies in different areas.
Solution Approach 2:
Different connection qualities are applied to different regions of the bonnet. The front zone has a looser connection (only at periphery) to allow flexibility and energy absorption during impact, while the rear zone has a stronger connection (with wedging cords) to maintain structural integrity. This local differentiation resolves the contradiction between overall strength and localized flexibility.
2Stability of the object's composition
If wedging cords are used to connect the inner lining to the outer skin, then the structural connection is improved, but the aesthetic appearance deteriorates due to visible marks on the outer skin
Solution Approach 1:
The wedging cords are extracted from the front zone and relocated to the rear zone. This removes the source of aesthetic degradation (visible marks on the outer skin in the front area) while preserving the structural connection function in the rear zone where visibility is less critical.
3Reliability
If the inner lining is crimped to the outer skin around the periphery and with wedging cords inside, then the connection reliability is improved, but the material usage increases and flexibility decreases
Solution Approach 1:
The connection strategy is segmented by zone: the front zone uses only peripheral crimping with no internal wedging cords, reducing material usage while maintaining sufficient reliability for the flexibility-critical area. The rear zone uses both peripheral crimping and internal wedging cords for enhanced reliability where flexibility is less critical.
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 improves pedestrian impact test results by cushioning the head and reducing injury risk while saving material and maintaining aesthetic appeal by eliminating the need for wedging beads.
Implementation Method 1
the inner liner is crimped to the outer skin around the periphery, in the front area and beyond 50 millimeters from the front edge of the cover
Implementation Method 2
They are made up of organic matter which freezes when the body of the vehicle is put in a cataphoresis oven during the anti-corrosion treatment of the vehicle
Data Source
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AI summary
The bonnet (10) has an inner liner (34) connected to an external skin (32), on a front zone (40) of the bonnet by a periphery (36) of the external skin. The front zone extends on a dimension of 250 millimeters with respect to a front edge (41) of the bonnet along a longitudinal direction of the vehicle. The inner liner is fixed to the external skin outside the front zone and inside the periphery of the skin, where the skin and the inner liner have virtually identical sizes.