What are fatigue tests?
Fatigue is a phenomenon whereby failure of materials under cyclic dynamic loads occurs more readily than under static loads.
Fatigue testing is a method for determining the behavior of materials under fluctuating loads. A specified average load (which may be zero) and an alternative load are applied to a specimen and the number of cycles required to produce a failure is recorded.
What is the objective of this type of testing?
Fatigue tests have a clear objective and that is to analyze the resistance characteristics of different materials when working under variable loads. Among these materials we can find rotating transmission shafts, anchor bolts, bars, various structures, rotating shafts, shock absorbers and even asphalt or bituminous mix (to see how deterioration evolves with the passage of time and progressive degradation).
Among the fundamental parameters that qualify the characteristic fatigue behavior of materials are:
- The kinetics of the applied load over time.
- Type of stresses generated in the part, as a consequence of the application of the load.
- Type of work characteristic of the part as a whole in the machinery.
Fatigue testing machines
At Servosis we have the latest machines for fatigue testing of materials, including the MUF 401 SERIES and the MUF 404 SERIES:
MUF 401 SERIES
Designed to satisfy the requirements in medium and high frequency tests, up to approx. 100 Hz. and with load capacities between 1 and 25 t.
They incorporate 2 columns on which the upper bridge slides, which is hydraulically operated and locked. From 20 t and above, and depending on the use to which the machine is to be dedicated, 4 columns can be mounted to achieve greater rigidity.
The hydraulic cylinder is normally mounted on the upper movable bridge, although it can be mounted on the lower bed on request.
This type of machine is equipped with a special type of servocylinder:
Mod CH-9, hydrostatic type. The sealing rings at the outlet are eliminated and a suction group for oil drainage is incorporated. Max. working freq. 100 Hz.
The stroke of the upper bridge is normally 800 mm. to adapt the axial span to different types of specimens to be tested.
A large number of test fixtures such as tensile grips, bending devices, etc. can be included.
The lateral span between columns is 500 mm, and if required, for example, in case of incorporating a climatic chamber, 800 mm.
MUF 404 SERIES
These frames are cyclic type in low and medium frequency.
Designed to comply with ISO 12106, UNE 36065 EX, LCF fatigue tests ASTM E606, etc. specifications.
The cylinder is always located on the upper bridge. All versions incorporate 4 columns.
This series incorporates hydraulically operated side clamping jaws of the 4013 ALH series.
One of the main uses for which these machines are designed is to perform tensile and cyclic tests on round metal specimens.
They are built for forces between 50 and 250t. For lower load capacities we would have the previous Series, the MUF-401, between 2 and 60t.
As with all our hydraulic frames, the upper bridge is hydraulically moved and locked, and the axial spans can be adapted to the type of tests to be performed, although the standard version is usually 700mm.
The type of cylinder used in this type of machine is the CH-4 type (quasi-static) for frequencies up to 10Hz. And CH_9 for higher frequencies, with variable strokes depending on the use for which the machine is intended, the standard is 200mm.
PCD2K software for control
Both machines are controlled by our PCD2K software, which provides the user with various options for their use:
The options of general use, with which the maximum possibilities of performance in the realization of tests are available. The customer can configure his test in a personalized way and process the data afterwards.
The test windows under customized standard, with which the maximum simplification in the performance of a specific test is available, by agglutinating in a single window only the elements necessary for the performance of this specific test, and obtaining directly the results of all the calculations indicated in the standard. These windows are always designed according to the needs of the test and the customer’s request.
As many test standards as desired can be installed in the same machine, with no other limitation than the maximum load capacity imposed by the machine and the maximum speed, determined by the hydraulic unit.
The test report will show the Standard under which the test was performed, the test parameterization, the machine data and the test results, as well as the Force/Strain graph.
If you are interested and want to know more about our fatigue tests, please check our fatigue machines section, and if you have any questions or suggestions you can contact us through the contact form.