What is Noise Vibration and Harshness Testing?

Noise Vibration and Harshness testing (NVH 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 Environmental Protection Agency, but also severe noise and vibration are harmful to the human body and can be detrimental to the structural integrity of almost all consumer goods. In order 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.

With the growing popularity of the electric car, automotive manufacturers will see an ever-increasing need to conduct NVH testing such asBuzz, Squeak & Rattle (BSR).鉴于缺乏发动机噪音，可能已经被忽视的许多声音现在可能会对客户变得滋扰，导致投诉和可能的回报。许多BSR问题可以在开发时期提前检测到具有简单的测试，例如通过开发的车辆轮廓或正弦扫描在一个消声室中的BSR振动器上运行组件。这些腔室设计成模拟“自由场”，其中允许声波在所有方向外自由传播但不返回。这种类型的测试可用于本地化不需要的声音的源或原因，允许制造商在产品成为保修期之前修改其设计。

BSR testing can be completed in one of two ways, subjectively or objectively. With a subjective evaluation, typically an individual or panel of individuals will listen to the noise generated by the structure under vibration and assess its perceived characteristics. Likewise, an objective test will utilize actual measurements along with hardware such as microphones to establish noise levels in several useful units including dBA, Sones, and so on.

NVH测试的另一个关键方面是模态分析。由于所有结构和机制（包括人体）固有地具有它们振动的共振，因此可以在尽可能识别和避免这些频率的关键。当系统在其共振频率振奋时，其振荡的振幅在其最大值，并且可能导致成分，疲劳甚至突然间的结构完整性损失的过早磨损。例如，飞机制造商必须符合FAA标题14 CFR部分23，该第23部分要求制造商在发布适航证书之前对所有机架进行地面振动测试来识别结构共振。此过程在所有新机构上完成，以及对现有设计的更改，因为对结构的任何修改都将改变其谐振的频率。

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.

元素提供的这些和其他类型的NVH测试包括：万博官网app体育

• Sound Power and Sound Intensity
• Natural Frequency Analysis
• 刚性体特性的测定（CG，惯性惯性轴）
• Sound Quality
• 旋转机械的订单跟踪和分析
• 转移路径分析
• Static and Dynamic Structural Stiffness

万博官网app体育元素专家使用行业领先的NVH测试方法，硬件和软件，以帮助我们的客户开发安全，质量，兼容，令人愉快的产品，以带来市场。

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