电磁式振动台随机振动试验目的与振动失效模式
Electromagnetic shaker random vibration testing and vibration failure mode

    产品在运输和实际使用中所遇到的振动，绝大多数是随机振动。例如，宇航器在发射和助推阶段的振动；火箭发动机的噪声和气动噪声使结构产生的振动；飞机（特别是高速飞机）的大功率喷气发动机的振动；飞机噪声使飞机结构产生的振动和大气湍流使机翼产生的振动；飞机着陆和滑行时的振动；车辆在不平坦的道路上行驶时产生的振动；多变的海浪使船舶产生的振动等，都属于随机振动。因此，用电磁式振动台随机振动试验机试验才能更真实反映产品的抗振性能。

Vibration products encountered in transport and in practical use, the vast majority of random vibration. For example, vibration spacecraft during launch and boost phase; vibration noise and rocket engine noise cause; aircraft (especially high-speed aircraft) the vibration of large jet engines; vibration of aircraft noise the aircraft structure vibration and atmospheric turbulence so that the wing produces vibration of aircraft landing and taxiing; the vibration of vehicle; driving on uneven road when changing the ship generated waves; vibration etc., all belong to the random vibration. Therefore, an electromagnetic shaker random vibration test can more truly reflect the anti vibration performance of the product.

    与正弦振动相比，随机振动试验机的频率域宽，而且有一个连续的频谱，它能同时在所对频率上对产品进行激励，各种频率的相互作用远比用正弦振动仅对某些频率或连续扫频模拟上述振动的影响更严酷、更真实、更有效。另外，用随机振动来研究产品的动态特性和结构的传递函数比用正弦振动的方法更为简单和优越。

Compared with the sinusoidal vibration, frequency domain random vibration test machine is wide, and there is a continuous spectrum, it can at the same time in the frequency of excitation, the interaction of various frequency than the sine vibration influence only on certain frequencies or continuous sweep frequency analog the vibration, more real, more severe more effective. In addition, the transfer function and dynamic characteristics of the structure of the product to use the random vibration of the sine vibration than method is more simple and superior.

    随机振动和正弦振动一样能造成导线摩擦、紧固件松动、活动件卡死，从而破坏产品的连接、安装和固定。当随机振动激励造成的应力过大时，会使结构产生裂纹和断裂，特别在共振状态下更为显著。长时间的随机振动，由于交变应力所产生的累积损伤，会使结构产生疲劳破坏。随机振动还会导致触点接触不良，带电元件相互接触或短路，焊点脱开，导线断裂，以及产生强电噪声等，从而影响产品的正常工作，使产品性能下降、失灵甚至失效。

Random and sinusoidal vibrations can cause wires friction, loose fasteners, stuck, thus destroying the connection, installation and fixation of the product. When the random vibration caused by stress is too large, will make the structure crack and fracture, especially in the resonance state is more significant. Random vibration of long time, accumulated damage due to alternating stress produced, make the structure fatigue damage. Random vibration will result in bad contact, electrical components are in contact or short circuit, the solder joint disengagement, wire breaking, and strong noise, which affects the normal work of product, make the product performance, failure or failure.

    随机振动试验机的描述：在随机振动试验中，由于电磁式振动的质点处于不规则的运动状态，永远不会地重复，对其进行一系列的测量，各次记录都不一样，所以没有任何固定的周期。在任何确定的时刻，其振幅、频率、相位都不能预先知道，因此就不可能用简单的周期函数和函数的组合来描述。

Random vibration test machine description: in random vibration test, because the particle electromagnetic vibration is in motion and irregular, never accuray repeat, a series of measurements were carried out on it, each record is not the same, so there is no fixed period. At any given moment, its amplitude, frequency, phase is not known in advance, so will not be a simple combination of periodic function and function to describe.

    随机过程：按功率谱谱密度频谱的形状，即按随机过程的频率结构，产品现场出现的随机振动主要有下列形式。宽带随机振动试验机是指振动的能分布在一个较宽的频率范围内的振动，一般运载工具，特别是空中运载工具，如喷气式飞机，其产生的振动就属于宽带随机振动。

Stochastic process: according to the power spectrum density spectrum shape, namely according to the frequency of random process, random vibration of the scene of the main products have the following form. Random vibration test machine broadband refers to the vibration energy distribution in a wide frequency range of vibration, the general vehicles, especially the air vehicles, such as jet aircraft, vibration the belongs to the broadband random vibration.

    窄带随机振动是指振动的能分布在一个较窄的频率范围内的振动，如螺旋桨飞机，由于螺旋桨叶转动时所带动的旋转压力场将产生窄带随机振动，窄带随杉l的中心频率是螺旋桨叶的通过频率及其谐波（一般到4阶），其窄带带宽为其通过频率（中心频率）及其各次谐波的5%(漂移）。宽带+窄带随机振动除窄带随机振动外，更主要的是各种振源引起的宽带随机振动。如安装在腫带车辆上和通过履带午:辆运输的产品，通常会经受到以宽带为主+窄带的随机振动。宽带随机振动来自车辆的基本运动、支承系统、路面不平。窄带随机振动来自履带拍击地面的运动。

Narrow band random vibration is vibration energy distribution in a narrow frequency range of vibration, such as propeller aircraft, due to the rotating pressure driven propeller blade rotation field will have a narrow band random vibration, narrow band with center frequency L is fir propeller blade passing frequency and its harmonics (typically 4 to order), the narrow bandwidth of the frequency (frequency) and the harmonic 5% (drift). Broadband and narrowband random vibration in addition to narrow band random vibration, more important is the broadband random vibration caused by various sources. Such as the installation of the swollen with vehicles and by afternoon: track transportation products, often subjected to random vibration to broadband based + narrowband. The basic motion, broadband random vibration from the vehicle's supporting system, uneven pavement. Narrow band random vibration from the track on the ground motion.

   宽带随机振动+周期振动宽带随机振动+周期振动是指在宽带随机振动上叠加正弦振动，直升飞机的振动往往是在宽带随机振动的签础上叠加很卨的正弦振动。宽带随机振动试验机来自直升飞机的各种振源，正弦振动是由直升飞机的旋转部件产生的，如主旋翼、尾旋翼、发动机和变速箱的振动。的国标和IEC标准，将宽带+窄带随机振动与宽带随机振动+周期振动，称为混合激励振动。在混合激励振动中，随机分量用加速度谱密度表示，正弦分量用加速度幅值表示。

Broadband vibration band random vibration and random vibration and oscillation cycle refers to the superposition of sine vibration in broadband random vibration, the helicopter vibration are sinusoidal vibration superposition is improve in sign based broadband random vibration. Various sources of broad-band random vibration test machine from the helicopter, sinusoidal vibration is generated by the rotating components of helicopter, such as the main rotor, tail rotor vibration, the engine and transmission. The new national standard and IEC standard, the wideband and narrowband random vibration and random vibration and periodic vibration, called hybrid excitation. In the mixed excitation vibration, random component by acceleration spectral density representation, expressed by the acceleration amplitude of sinusoidal components.