Understanding Sine Vibration & Random Vibration Testing

Sine Vibration Testing

There are many different types of vibration testing. Each vibrational test protocol is established to meet specific goals within the testing environment. Two of the most common types of vibrational testing include sine vibration and random vibration. To know which type of test is best for your product you must first understand what your test is hoping to reveal.

There are virtually as many different adjustments for each type of vibration testing as there are ranges in which an object can be tested. Often, the determining factor in which type of vibration test is best is the end-use environment of the product. For example, if a product is used in an environment where reciprocating equipment, such as a motor or turbine are able to transfer vibrational energy to the product being tested, it is important to understand what kind of resonate vibration will trigger failure. This is the predominant goal of sine vibration testing.

Sine testing uses a single frequency and alters the amplitude to the product’s natural resonance. Since this resonance will multiply the vibrational stress experienced by the part under test, targeting this frequency with increased amplitude will simulate expected vibrations a product will experience over its usable lifetime. Sine vibration testing will dwell on the same resonate frequency and allow the natural properties of the material to react to the vibration stimulus.

When performing sine vibration testing on a product with multiple types of materials, it is often best to use a swept sine vibration test. In this method, there is still an attempt to find the natural resonate characteristics of the product, but the vibration frequency is gradually altered over a specified rate and duration. This allows the test to identify the resonate frequencies of each part in the product. With assemblies such as electrical circuit boards, for example, the individual modules connected to the board may have a different resonate responsiveness than that of the circuit board itself. Using the swept sine test will allow a test technician to fine tune the vibrations to the frequencies which will give the most effective results across multiple vibration spectrums.

Sine and swept sine testing are often used for design verification and durability testing. When each of these tests trigger the product’s resonate frequency, the vibration is multiplied by the natural response to the supplied vibration. As the vibrational force multiplies, any weaknesses in design or incompatible assemblies will be identified, often through the means of some form of product failure.

Random Vibration Testing

Random vibration testing is often used for validation or verification of a product’s compliance to specific regulatory testing standards. Random vibration testing applies vibrational force over all frequencies within a specified range. While random vibration testing is best utilized when the vibration environment of the end-use location is known, often testing standards such as MIL-STD-810G, for example, can provide a suggested frequency range to achieve compliance. Random vibration testing is measured using accelerometers which identify the range of force applied using G/rms.

With random vibration, you will find a more realistic, real world vibration signature than that of sine vibration testing. By altering the amplitude, duration or frequency of the random vibration test, a reasonable assumption is made as to the amount of stress a product can withstand during a given time period.

Our Vibration Testing Services

At CSZ Testing Services, our expertly trained test technicians are able to provide vibration testing services which meet both sine and random test protocols. We are A2LA accredited; ITAR registered and have a proven track record in providing timely and accurate test results.

To speak with one of our technicians or to request a quote, please contact us at testlab.na@weiss-technik.com, or visit us on the contact page.