View Application Notes Based on Common Questions Received from Customers
In packaging test, it is very important to do Force / Deflection test, the bad packing deflection may cause damage of the products. VENZO 800 series vibration controller provides Force / Deflection function, which scales the recorded acceleration to Force and computes & analysis the position change (deflection) relative to the accelerometer mounting.
According to the purpose of vibration test to divide the vibration tests into following types, environmental adaptability test, dynamic strength test, dynamic characteristics test and other purpose vibration test.
Analysis of the shock time history as a digital sequence can be performed using the Shock Response Spectra (SRS). This paper will emphasize on the condition that measured data not available, according to MIL-STD 810G, then for Procedure I – Functional Shock, and Procedure V - Crash Hazard Shock Test, employ the applicable SRS spectrum from Figure 1 as the test spectrum for each axis, provided Te of the test shock time history falls between the values in the accompanying Table 1.
The purpose of Resonance Search, track and dell test is usually for fatigue and durability test, it always can find and test the weakest frequency point of test unit, the dwell methods include locked frequency, locked phase, peak amplitude tracking and phase tracking. The latter three methods frequency will be varied during the tracking and dwelling phase, since as we know the resonant frequency is true decreasing during dwelling period, while phase is not, so these three methods maybe better in catching with the resonance point. This paper will analyze results between fixed frequency dwell and phase tracking dwell, emphasizing on phase tracking and introduce how to do this test with VENZO controller VibExpert software.
As we all know, before doing vibration testing, we should edit the reference spectrum with the vibration controller, usually low frequencies with constant displacement spectrum, middle frequencies with constant velocity spectrum, while the high frequencies with constant acceleration spectrum. This method has some relationships with vibration control algorithm; on the other hand, we can study the amplitude conversion relationship among acceleration-speed-displacement to understand the principle.
Sine-on-Sine vibration testing is multi-frequency sine testing, which allows multiple sine tones simultaneously excited in the same testing. This method has become much more popular since a consortium of German automobile manufacturers like BMW approved the use of multiple simultaneous swept sine tones to reduce the time and cost of durability testing.
In recent years there has been a rapidly developing interest in the field of mechanical dynamics for a variety of reasons. Firstly, the development of stronger materials and greater economy in design has led to increasingly lighter structures, more prone to vibration problems. At the same time, increasing rotational speeds also give increasing likelihood of having to deal with structural resonances.
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.
In physics, resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others. Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies, or resonance frequencies. At these frequencies, even small periodic driving forces can produce large amplitude oscillations, because the system stores vibrational energy.
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