Composite Rear Shelf Module Tuned Stiffness
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Solution Overview
Problem
Automotive interior modules, such as rear shelf assemblies, are labor-intensive to assemble and conduct sound, negatively impacting vehicle acoustics, necessitating a lighter weight alternative that enhances modularity, reduces part numbers, and dampens noise.
Innovation Solution
A composite rear shelf module formed of a reinforced multilayer, multi-laminate fiber-reinforced plastic composite structure with selectively oriented continuous and discontinuous fiber reinforced thermoplastic layers, integrated vehicle attachment members, and tuned stiffness and mass to avoid resonance with speakers, along with foam sandwich structures and ribbing to reduce noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional metal stampings and spot welding are used, then structural strength is achieved, but assembly time and labor intensity increase
Solution Approach 1:
The patent combines multiple separate metal stampings and components into a single integrated composite module. The fiber-reinforced plastic composite structure integrates the shelf panel, reinforcement ribs, and attachment members into one monolithic component, eliminating the need for spot welding multiple parts together and significantly reducing assembly time and labor intensity
Solution Approach 2:
The composite module serves multiple functions simultaneously: it provides structural support, acts as a sound barrier, integrates attachment points for speakers and subwoofers, and includes built-in reinforcement features. This multi-functionality reduces the number of separate parts needed and simplifies the overall assembly process
2Object-affected harmful factors
If metal members are used, then structural strength is achieved, but sound conduction increases negatively impacting vehicle acoustics
Solution Approach 1:
The patent uses fiber-reinforced plastic composite materials that combine the structural strength needed for load-bearing applications with the acoustic damping properties of composite construction. The layered composite structure with fiber reinforcement provides both mechanical strength and sound insulation, eliminating the sound conduction problems associated with solid metal members
Solution Approach 2:
The composite module acts as an intermediary between the vehicle trunk and passenger compartment, providing acoustic isolation. The fiber-reinforced plastic material serves as a mediator that blocks sound transmission while maintaining structural integrity, preventing harmful sound conduction from the trunk area into the passenger cabin
3Weight of moving object
If weight is reduced by 40%, then fuel efficiency improves, but structural strength may be compromised
Solution Approach 1:
The fiber-reinforced plastic composite material provides high strength-to-weight ratio, enabling significant weight reduction compared to conventional metal modules while maintaining or even improving structural strength. The directional fiber orientation and composite construction provide exceptional strength where needed without the excess weight of metal
Solution Approach 2:
The composite module features locally optimized fiber orientation and thickness distribution, with reinforced areas positioned precisely where structural strength is needed and thinner sections where weight reduction is prioritized. This local quality optimization achieves overall weight reduction while maintaining structural integrity in critical areas
4Object-affected harmful factors
If natural frequencies are tuned outside speaker working range, then resonance is avoided, but design complexity increases
Solution Approach 1:
The patent employs parameter optimization by tuning the natural frequencies of the composite module through adjustments in material properties, thickness, and geometric configuration. By changing these parameters, the natural frequencies are shifted outside the speaker operating range, preventing resonance without requiring complex active control systems or additional damping components
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 composite module provides structural strength, reduced noise and vibration, lower weight, and simplified assembly, enhancing vehicle acoustics and reducing manufacturing costs while meeting design criteria.
Implementation Method 1
various thicknesses, foam sandwich structures, and ribbing may be utilized to 'tune' the natural frequencies of the motor vehicle part (e.g., shelf) to be outside an excitation range of components on the shelf (e.g., speakers)
Implementation Method 2
The composite panel constructed in accordance herein may substantially reduce the noise from internal components (e.g., speakers) and from the trunk area with respect to the cabin noise levels in the vehicle
Data Source
AI summary
A composite module for a vehicle may be both a structural member and include a finished surface. In at least some embodiments, a composite rear shelf module includes a panel with a reinforced multilayer, multi-laminate fiber reinforced plastic composite structure. The panel may include selectively orientated, continuous fiber reinforced thermoplastic composite layers and/or the panel may include discontinuous fiber reinforced thermoplastic reinforcements. The composite rear shelf module may include a show surface film with a class-A surface, eliminating the need for a separate layer of carpet or other material. In some embodiments the module has vehicle attachment members for securing the module to the vehicle body, and the stiffness and mass of the module and the arrangement of the vehicle attachment members and reinforcements are tuned to move the natural modes, or natural frequencies, of the panel outside the working frequency range of any speakers or subwoofers.