In the field of sensor testing and measurement, the prerequisite for accurately capturing signals is to create an "interference-free" environment. Vibration and noise reduction equipment must not only mitigate the interference from vibrations and noise but also eliminate its own impact on the testing system through "stealth design." This "stealth feature" has become the core competitiveness of high-end testing equipment.
Material innovation is the foundation for achieving equipment stealth. The polyvinyl alcohol/carbon composite aerogel developed by South China University of Technology, through a multilayer hierarchical structure design, can reduce the buzzer noise from 77.2 decibels to 62 decibels while achieving broadband microwave absorption at 12.7GHz, with a radar cross-section as low as -52dBsm. The mechanical metamaterial developed by the team at the National University of Defense Technology effectively addresses the weak low-frequency regulation capability of traditional materials by utilizing microstructure modulation to form soft deformation resonance, providing critical support for underwater acoustic stealth testing. These materials absorb vibration noise while avoiding becoming new electromagnetic or acoustic reflection sources themselves.
Structural optimization forms the core defense line for equipment stealth. The active vibration damping system, through modular design, extends the vibration suppression frequency range from 0.5Hz to several hundred Hz, with built-in sensors and actuators achieving response delays in the millisecond range, avoiding additional signal interference. The low-frequency broadband metamaterial radial damping bearing targets rotating sensor testing scenarios, utilizing the periodic structure of phononic crystals to mitigate shaft system vibrations while reducing acoustic radiation, ensuring the stealth requirements for propulsion system testing of underwater vehicles. Air spring damping technology further controls vibration amplitudes within ±0.5μm, creating a "zero-vibration" foundation for lithography machine sensor testing.
System integration technology enhances the closed-loop characteristics of stealth. In the signal transmission process, composite shielding cables adopt a "aluminum foil + high-permeability magnetic material + copper mesh" structure, achieving a shielding effectiveness of over 100dB. Combined with single-end grounding technology, interference can be reduced by 32dB. The intelligent monitoring system optimizes equipment operational parameters in real time through online shielding integrity detection and adaptive filtering adjustment, preventing self-generated electromagnetic signals from invading the test loop. In a petrochemical project, the vibration and noise reduction equipment optimized through system integration reduced signal attenuation over a 200-meter transmission distance from 35% to 8%, while keeping interference levels below 50mV.
Looking ahead, the stealth characteristics of vibration and noise reduction equipment will advance toward multidimensional development. At the level of technological integration, the combination of artificial intelligence and adaptive control has become a core trend. Through deep neural network algorithms, real-time identification of noise and vibration sources can be achieved, enabling dynamic adjustment of material damping properties and structural response parameters to maintain an "uninterrupted" state even under complex working conditions. An intelligent vibration damping platform developed by a laboratory has achieved adaptive regulation across the 0.1Hz-1kHz frequency range, with interference suppression accuracy improved by 40% compared to traditional equipment.
Material technology will advance toward multifunctional integration, with the development of novel materials that combine broadband vibration absorption, electromagnetic shielding, and eco-friendly properties becoming a key focus. Environmentally friendly products such as bio-based polyurethane and recyclable damping materials are gradually entering pilot production stages, and are expected to achieve a penetration rate of over 35% in high-end testing applications within the next five years. Meanwhile, nanoscale microporous structural design can further extend the frequency response range of materials, providing stealth support for terahertz-band sensor testing.
In system design, multi-domain collaborative stealth has emerged as a new direction. Through interdisciplinary simulation and optimization involving acoustics, electromagnetics, and structural mechanics, vibration suppression, noise absorption, and electromagnetic silence can be achieved simultaneously. For instance, in aerospace sensor testing, integrated stealth equipment can simultaneously control mechanical vibration amplitudes to within 0.1μm and reduce electromagnetic radiation intensity to below 10μV/m, meeting multi-dimensional testing requirements.
From material invisibility to structural invisibility, and further to system invisibility, the development of vibration and noise reduction equipment has consistently centered on the core goal of "eliminating interference without introducing new disturbances." In high-end testing fields such as semiconductor inspection and underwater acoustic detection, this invisibility characteristic directly determines the breakthrough boundary of sensor precision. Meanwhile, the future evolution toward intelligent, multifunctional, and collaborative technologies will provide stronger support for advancing testing and measurement techniques toward nanoscale, broadband, and high-sensitivity directions.