What is Noise Vibration and Harshness 测试?

Noise Vibration and Harshness testing (噪音 testing) is a critical component of any product during its design and development phase. Not only do manufacturers need to meet established requirements laid out by governing bodies such as The 环境 Protection Agency, but also severe noise and vibration are harmful to the human body and can be detrimental to the 结构 integrity of almost all consumer goods. To make products that last longer and sound better, physical testing should accompany all FEA models to ensure proper correlation, as well as give confidence in the design.

The automotive industry is steadily moving toward a greener future with increased focus on electric vehicles. For these vehicles to be as safe and comfortable as their 气体-powered counterparts, they must also undergo 噪音 testing such as Buzz Squeak Rattle (BSR). 考虑到电动汽车没有发动机噪音, many sounds that may have gone unnoticed in their 气体-powered counterparts may now become a nuisance to customers, leading to complaints and possible returns. Many BSR problems are easily detectable early in the development period with simple testing such as running a component through developed vehicle profiles or sine sweeps on a BSR shaker in an anechoic chamber. These chambers are designed to mimic a “Free Field” in which sound waves are permitted to propagate freely in all directions outwards but not return. This type of testing can be useful in localizing the source or cause of an unwanted sound, allowing manufacturers to modify their designs before the product becomes a warranty issue.

BSR testing can be completed in one of two ways, subjectively or objectively. 主观评价, typically an individual or panel of individuals will listen to the noise generated by the structure under vibration and assess its perceived characteristics. 同样的, an objective test will use actual measurements along with 硬件 such as microphones to establish noise levels in several useful units including dBA, Sones, 等等.......

Another critical aspect of 噪音 testing is Modal Analysis. Since all structures and mechanisms (including the human body) inherently have resonances to which they vibrate at, it is key to identify and avoid these frequencies whenever possible. When a system is excited at its resonance frequency, the amplitude at which it oscillates is at its maximum and can lead to premature wear of components, 乏力, or even sudden total loss of 结构 integrity. 例如, aircraft manufacturers must comply with FAA Title 14 CFR Part 23, which requires the manufacturer to undergo ground vibration testing of all airframes to identify the structures resonances before an airworthiness certificate is issued. This process is completed on all new airframes, as well as changes to existing designs as any modifications to the structure will change the frequencies at which it resonates.

There are two principal methods in which modal analysis is conducted, either with force input via a modal tuned hammer or an electrodynamic shaker. Selecting the best option for structure excitation and boundary conditions to apply depends upon the structure tested and the specific data set of interest to product designers and developers. Regardless of the excitation method chosen, the primary information extracted is relatively the same, with resonances identified via the Frequency Response Function (FRF), between the force input and acceleration output on the structure.

These and other types of 噪音 testing offered by im体育APP include:

• 声功率和声强
• 固有频率分析
• Determination of Rigid Body Properties (CG, Moments & 惯性主轴
• 音质
• Order tracking and analysis for rotating machinery
• 传递路径分析
• 静态和动态结构刚度

im体育APP experts use industry leading 噪音 testing methods, 硬件, and software to assist our customer in developing safe, 质量, 兼容的, and enjoyable products to bring to the marketplace.

Contact us today to talk to an expert or request a quote.