Burnout Test

Almost every known material is exposed to fatigue. This applies to polymers, plastics, composites and metals.

Metals tend to fatigue and deteriorate in fewer cycles than their plastic or polymer counterparts. This is because the cyclic deformation of metals disrupts the microscopic arrangement of the crystal grains and causes them to give with an increasingly lower amount of stress. Each deformation can eventually lead to failure.

Fatigue failure can also occur with cyclic loading, as repeated stresses concentrate on microscopic cracks that are inevitably present in every material except monocrystalline superalloys. This causes the stretched material at the roots of the cracks to be cyclically dispensed. Every yield or deformation in the material at the root of a particular crack leads to a weakening of the material, which causes the crack to deteriorate to the point of breaking. Bolts, studs and threaded connectors are particularly prone to this malfunction mode because their teeth are concentrated in stress. For this reason, bolts or studs used in the machines should be torqued according to the appropriate properties to preload them and reduce the cyclic tension amplitude.

Unfortunately, fatigue failure is an inevitable fact. Regardless of the amount of cyclic loading, there is no known way to design something that will ultimately fail due to fatigue. However, the best design practice will produce sufficiently fatigue-resistant products and structures to ensure a long and reliable service life. Best design practices often involve testing, and if fatigue errors affect your products, EUROLAB provides fatigue testing services that can help.

Understanding the Fatigue Test Process

In a way, the fatigue test is like bending a paper clip back and forth and counting how many times it can bend before it breaks. Therefore, a fatigue test involves repeatedly loading and unloading a test sample to evaluate how it will perform over time in its intended use environment.

To apply a valid fatigue test and analysis program, the following parameters must be determined:

• Identify the points where cyclic stress should be applied and the type of stress that should be applied to these points.
• Determine the number of cycles the test sample is expected to experience during its designed design life.
• Determine the amount of stress expected for each cycle during the intended life of the test sample.

Once these parameters are determined, the fatigue test process is relatively simple. EUROLAB testers can develop a customized fatigue test and analysis program to assess how your manufacturing materials will withstand the cyclic stress of their intended applications.

For more information on our material fatigue testing services, please contact us today.