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電磁式振動臺隨機振動試驗目的與振動失效模式
電磁式振動臺隨機振動試驗目的與振動失效模式
Electromagnetic shaker random vibration testing and vibration failure mode
產品在運輸和實際使用中所遇到的振動，絕大多數(shù)是隨機振動。例如，宇航器在發(fā)射和助推階段的振動；火箭發(fā)動機的噪聲和氣動噪聲使結構產生的振動；飛機（特別是高速飛機）的大功率噴氣發(fā)動機的振動；飛機噪聲使飛機結構產生的振動和大氣湍流使機翼產生的振動；飛機著陸和滑行時的振動；車輛在不平坦的道路上行駛時產生的振動；多變的海浪使船舶產生的振動等，都屬于隨機振動。因此，用電磁式振動臺隨機振動試驗機試驗才能更真實反映產品的抗振性能。
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.
與正弦振動相比，隨機振動試驗機的頻率域寬，而且有一個連續(xù)的頻譜，它能同時在所對頻率上對產品進行激勵，各種頻率的相互作用遠比用正弦振動僅對某些頻率或連續(xù)掃頻模擬上述振動的影響更嚴酷、更真實、更有效。另外，用隨機振動來研究產品的動態(tài)特性和結構的傳遞函數(shù)比用正弦振動的方法更為簡單和*。
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.
隨機振動和正弦振動一樣能造成導線摩擦、緊固件松動、活動件卡死，從而破壞產品的連接、安裝和固定。當隨機振動激勵造成的應力過大時，會使結構產生裂紋和斷裂，特別在共振狀態(tài)下更為顯著。長時間的隨機振動，由于交變應力所產生的累積損傷，會使結構產生疲勞破壞。隨機振動還會導致觸點接觸不良，帶電元件相互接觸或短路，焊點脫開，導線斷裂，以及產生強電噪聲等，從而影響產品的正常工作，使產品性能下降、失靈甚至失效。
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.
隨機振動試驗機的描述：在隨機振動試驗中，由于電磁式振動的質點處于不規(guī)則的運動狀態(tài)，永遠不會地重復，對其進行一系列的測量，各次記錄都不一樣，所以沒有任何固定的周期。在任何確定的時刻，其振幅、頻率、相位都不能預先知道，因此就不可能用簡單的周期函數(shù)和函數(shù)的組合來描述。
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.
隨機過程：按功率譜譜密度頻譜的形狀，即按隨機過程的頻率結構，產品現(xiàn)場出現(xiàn)的隨機振動主要有下列形式。寬帶隨機振動試驗機是指振動的能分布在一個較寬的頻率范圍內的振動，一般運載工具，特別是空中運載工具，如噴氣式飛機，其產生的振動就屬于寬帶隨機振動。
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.
窄帶隨機振動是指振動的能分布在一個較窄的頻率范圍內的振動，如螺旋槳飛機，由于螺旋槳葉轉動時所帶動的旋轉壓力場將產生窄帶隨機振動，窄帶隨杉l的中心頻率是螺旋槳葉的通過頻率及其諧波（一般到4階），其窄帶帶寬為其通過頻率（中心頻率）及其各次諧波的5%(漂移）。寬帶+窄帶隨機振動除窄帶隨機振動外，更主要的是各種振源引起的寬帶隨機振動。如安裝在腫帶車輛上和通過履帶午:輛運輸?shù)漠a品，通常會經受到以寬帶為主+窄帶的隨機振動。寬帶隨機振動來自車輛的基本運動、支承系統(tǒng)、路面不平。窄帶隨機振動來自履帶拍擊地面的運動。
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.
寬帶隨機振動+周期振動寬帶隨機振動+周期振動是指在寬帶隨機振動上疊加正弦振動，直升飛機的振動往往是在寬帶隨機振動的簽礎上疊加很卨的正弦振動。寬帶隨機振動試驗機來自直升飛機的各種振源，正弦振動是由直升飛機的旋轉部件產生的，如主旋翼、尾旋翼、發(fā)動機和變速箱的振動。的國標和IEC標準，將寬帶+窄帶隨機振動與寬帶隨機振動+周期振動，稱為混合激勵振動。在混合激勵振動中，隨機分量用加速度譜密度表示，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.