Abstract
The work at hand focuses on an adaptive system aimed at improving the soundproof performance of car door seals at specific regimes (cruise), without interfering with the conventional opening and closing operations. The idea addresses the necessity of increasing seal effectiveness, jeopardized by aerodynamic actions that strengthen as the speed increases, generating a growing pressure difference between the internal and the external field in the direction of opening the door, and then deteriorating the acoustic insulation. An original expansion mechanism driven by a shape memory alloy (SMA) wire was integrated within the seal cavity to reduce that effect. The smart material was activated (heated) by using the Joule effect; its compactness contributed to the realization of a highly-integrable and modular system (expanding cells). In this paper, the system development process is described together with the verification and validation activity, aimed at proving the functionality of the realized device. Starting from industrial requirements, a suitable solution was identified by considering the basic phenomenon principle and the allowable design parameters. The envisaged system was designed and its executive digital mock-up (CAD, computer-aided design) was released. Prototyping and laboratory tests showed the reliability of the developed numerical models and validated the associated predictions. Finally, the system was integrated within the reference car. To demonstrate the insulation effect, the experimental campaign was carried out in an anechoic room, achieving significant results on the concept value.
Highlights
A critical aspect the automotive industry is currently facing is represented by the abatement of the environmental impact of vehicles, in compliance with increasingly stricter regulations that include, among others, chemical and acoustic pollution aspects [1].With the aim of matching environmental issues and, at the same time, consolidating their role in the market, automotive companies are turning their attention to new technologies characterized by an adequate level of maturity to assure a competitive and quick diffusion of their products
No additional strain gage was used for temperature correction, since such tests were performed without shape memory alloy (SMA) and the correlated thermal load; compensations were implemented through the corrective coefficients defined by the manufacturer for the adopted strain gage (EP-08-125BT, Micro-Measurements, Vishay Precision Group Inc, Malvern, PA, USA), characterized by an annealed constantan foil with tough high-elongation polyimide backing and strain range up to about 20% at temperatures between −75 ◦ C to +205 ◦ C
Proposed architecture implemented SMA technology and was based on arrays of expanding cells integrated within a seal cavity
Summary
A critical aspect the automotive industry is currently facing is represented by the abatement of the environmental impact of vehicles, in compliance with increasingly stricter regulations that include, among others, chemical and acoustic pollution aspects [1]. CO2NTROL project [16], piezo shunted resonators assessed by Liao and Sodano [17] or Ciminello et al [18], SMA-based architectures for dynamic structural response modulation introduced by Ameduri et al [19]) Within this scenario, SMA technology shows great potential, and is currently the object of a wide research effort worldwide, ranging from modeling to implementation aspects. This paper follows a publication by the same authors [31] that gave a preliminary overview of the developed research This version reports a detailed description of that investigation, introducing unpublished aspects of numerical finite element (FE) simulations and experimental SMA system characterization, and providing an extended description of the assessed device and its operating mode. SMA-based system to produce the desired insulation improvement on an actual car, through direct measurements of the sound transmission reduction within a semi-anechoic chamber
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