How to select testing equipment according to lEC 60068 standard-Vibration Test

Vibration Test

IEC 60068 Standard

IEC 60068 is one of the standard series on environmental testing issued by the International Electrotechnical Commission. The IEC 60068 standard series provides a series of environmental test methods for electronic and electrical products to evaluate their performance and reliability under various environmental conditions. The IEC 60068 standard series consists of multiple parts, each part covering different environmental test methods and parameters. The main topic of this section is vibration testing.

01 IEC 60068-2-6&IEC 60068-2-64

IEC 60068-2-6 gives a method of test applicable to components, equipment and other articles which, during transportation or in service, may be subjected to conditions involving vibration of a harmonic pattern, generated primarily by rotating, pulsating or oscillating forces such as occur in ships, aircraft, land vehicles, rotorcraft and space applications or are caused by machinery and seismic phenomena. This standard consists basically of subjecting a specimen to sinusoidal vibration over a given frequency range or at discrete frequencies, for a given period of time. A vibration response investigation may be specified which aims at determining critical frequencies of the specimen.

The purpose of this test is to determine any mechanical weakness and/or degradation in the specified performance of specimens and to use this information, in conjunction with the relevant specification, to decide upon the acceptability of the specimens. In some cases, the test method may also be used to demonstrate the mechanical robustness of specimens and/or to study their dynamic behavior. Categorization of components can also be made on the basis of a selection from within the severities quoted in the test.

Frequency range

The specification shall select a lower frequency from Table 1 and an upper frequency from Table 2 to determine the frequency range. Recommended frequency ranges are shown in Table 3

Table 1 Lower Frequency

Table 2 Upper Frequency

Table 3 Recommended Frequency Ranges

IEC 60068-2-64 demonstrates the adequacy of specimens to resist dynamic loads without unacceptable degradation of its functional and/or structural integrity when subjected to the specified random vibration test requirements. Broadband random vibration may be used to identify accumulated stress effects and the resulting mechanical weakness and degradation in the specified performance. This information, in conjunction with the relevant specification, may be used to assess the acceptability of specimens.

This standard is applicable to specimens which may be subjected to vibration of a stochastic nature resulting from transportation or operational environments, for example in aircraft. space vehicles and land vehicles. It is primarily intended for unpackaged specimens, and for items in their transportation container when the latter may be considered as part of the specimen itself. However, if the item is packaged, then the item itself is referred to as a product and the item and its packaging together are referred to as a test specimen.

Figure 1-Tolerance bands for acceleration spectral density; initial and final slop

Figure 2-Time history of stochastically excitation; probability density function with Gaussian (normal) distribution

Figure 3-Statistical accuracy of acceleration spectral density versus degrees of freedom for different confidence levels

02 KRD70 Hydraulic Vibration Shaker

KRD70 series hydraulic vibration shaker converts the energy of high-pressure liquid into the power of the reciprocating motion of the cylinder through the electro-hydraulic servo valve. Especially suitable for vibration tests requiring low frequency and high force. It can realize sine, random, multi-point excitation and shock test (sine, random, sine on random, random on random, or resonant search & dwell). It’s applied for reproducing the vibrations of transportation vehicles, bulk packaging products, machinery, electrical and electronic products in the actual environment, thereby optimizing the product structure and saving costs.

Electro-hydraulic servo vibration has the advantages of fast response speed, high anti-load rigidity, flexible control mode, etc. Its exciting force can reach hundreds of thousands of newtons, and large displacement amplitudes can be obtained, and the maximum displacement can reach more than 2 meters. The structure is small but firm, and is able to withstand horizontal load. Electro-hydraulic servo vibration is a control system that uses hydraulic power components as actuators, according to the principle of closed-loop feedback, which makes the output of the system track a given signal, and can transform and amplify the input. It is suitable for testing all kinds of products in aviation, marine, automotive, earthquake and other industries.

The hydraulic vibration table can perform vibration test, which can be applied to:

u  Design product packaging to better meet the needs of the actual environment;

u  Evaluate the damage resistance and fatigue performance of products and components;

u  Reduce the probability of product damage caused by transportation;

u  Save product maintenance costs

Features

u  To achieve sine vibration, random vibration, multi-point excitation, and shock and bump;

u  It can be used to simulate seismic excitation with low frequency and high force features;

u  The high-strength cast aluminum or cast magnesium table ensures uniform and consistent vibration, high reproducibility, and avoids deformation of the table.

Sine Test

Random Test