Random vibration is unpredictable but present in many mechanical and electrical systems. Engineers use statistical data to simulate and design products to withstand random vibrations, such as those experienced by cars on highways and rocket launches. Statistics can provide information on mean values and standard deviations, which can be used to replicate vibration conditions in a laboratory. Rocket payloads experience initial spikes of vibration from engine firing, shock waves, and aerodynamic effects, which must be accounted for in design.
Random vibration is any vibration that does not follow a pattern. It is present to some extent in a wide variety of mechanical and electrical systems. While random vibrations cannot be predicted exactly, statistics can generate useful information for vibration environments. Cars on the highway and rocket launch are two situations that can face intense random vibrations. Engineers use statistical data to simulate this vibration in the laboratory.
It is often possible to predict certain probabilities of random vibration behavior. For example, if a car on the highway vibrates randomly in a vertical direction, its future position relative to the ground cannot be known exactly. However, the probability of the car exceeding a certain height can be predicted. This is possible because random behavior follows a normal distribution or “bell curve”. The behavior of such a system can be analyzed with the tools of statistics.
Statistical analysis can provide information such as the mean value of many measurements. In the car example, the average ground clearance might be something like 1 foot (30.5 cm). In a large enough sample of measurements, statistics can also provide standard deviations. A standard deviation is the distance from the mean value that contains 68.2% of all data points. For the car vibration test, 68.2% of the height measurements could be within 1 inch (2.54 cm) of the average height.
Once the standard deviation of test data is calculated, engineers can use it to design products. The random vibration conditions on many different highways are similar, so the statistics are quite reliable. Engineers use this data to replicate vibration conditions in a laboratory, where it is easier to test different product designs.
Another situation that experiences random vibrations is a rocket launch. Rocket payloads feel an initial spike of vibration as the engine fires. Seconds later, the vibrations are mostly from the burning engine. After the rocket exceeds the speed of sound, the vibrations result mainly from shock waves and aerodynamic effects on the vehicle. Subsequently, some vibration may result from smaller thrusters correcting the orientation of the rocket.
As with the car, rockets and their payloads must be designed to survive random vibrations. Engineers need to know vibration statistics so they can reproduce these conditions in the laboratory. It would be impractical to launch a test rocket every time a new payload design needs to be tested. Rather, engineers put sensors on rockets as they launch and then use this data at a later time.
Protect your devices with Threat Protection by NordVPN
