Enhanced lightweight NVH solution based on vibro-acoustic metamaterials

The NVH performance of conventional panels and structures is mainly driven by their mass. Vibro-acoustic metamaterials with stopband behaviour are looked upon as a possible solution for combing NVH and lightweight requirements for engineering structures. This contribution discusses a metamaterial concept based on sandwich structures with embedded resonant structures that exhibit vibro-acoustic stopband behaviour. This potential is shown through the design and measurement results of two demonstrators. First a metamaterial encapsulation is designed and produced to showcase the potential of this type of metamaterials to improve acoustic insulation performance in targeted frequency ranges. Second a graded metamaterial strip is designed; this strip is built as a combination of metamaterials with different design frequencies, opening up the potential for broadband vibration reduction in a low frequency zone. These metamaterials can be achieved through a variety of designs or production processes, depending on the application, and can offer technological benefits such as possible integration in structural parts, use in harsh environments and ease of design of the beneficial frequency ranges, paving the way for a new class of light and compact NVH solutions with ample applications in automotive for low and mid frequency NVH mitigation.