Resonant Versus Servohydraulic: What’s the best way to fatigue test your components?

In manufacturing, a product is only as good or bad as its weakest link. So, it’s imperative that companies find it and eliminate it as early as possible in the production cycle. And one of the best ways to do that is fatigue testing.

Why every industry does it

Fatigue testing is widely used across various industries particularly in the fields of engineering and structural design that deal with the design, production, and maintenance of materials. As the name implies, the tests are used to generate fatigue or demonstrate the safety of a structure susceptible to fatigue. It involves subjecting components to cyclic loading to simulate real-world operating conditions to evaluate durability.

In the automotive industry, for example, fatigue testing helps evaluate the durability of components such as engine parts, suspension systems, and tires, while in the aerospace sector, landing gear and turbine blades are often put to the test. In manufacturing gears, bearings, and shafts are routinely put through fatigue testing. The medical device industry too uses fatigue testing while developing prosthetics or cardiovascular devices as they help to assess life expectancy and strength of components.

What are the types of fatigue testing?

The primary types of fatigue testing are resonance fatigue testing and servohydraulic testing. So, let’s do a comparison of the two:

 

Parameters	Resonance or vibration fatigue testing	Servohydraulic testing
What it is	Involves stimulating a test specimen near its primary vibration mode by applying a rotating radial force to one end	Involves applying cyclic loads to the specimen using a hydraulic actuator
Advantages	It is reliable, quick, and efficient. For instance, it tests the full circumference of girth welds and mechanical connectors in full-scale pipes. Because it uses an excitation force close to the natural frequency of the material, it is quick and reduces the overall testing duration	Force and displacement are precisely controlled throughout the test, allowing for accurate determination of fatigue life and behaviour. It offers versatility and accuracy, allowing for the simulation of complex loading conditions that resemble real-world operating conditions. Can be customised to meet specific testing requirements
Limitations	Requires precise control of the excitation frequency, which can be challenging for materials with multiple resonance frequencies. Also, it is primarily applicable to low-cycle fatigue (LCF) testing, where the number of cycles to failure is relatively small. For high-cycle fatigue (HCF) testing, where a large number of cycles are required, it may not be as effective	Generally slower compared to resonant testing and can result in longer testing cycles. The cost of servohydraulic testing equipment can be higher compared to resonant testing
Where it is used	Oil and gas industry for testing girth welds in risers, pipelines, and flowlines. Also used in aerospace	Primarily used in automotive, steel, plastic, and medical device  industries
Well-suited for	Testing a wide range of materials and structures, including metals, composites, and large-scale components	Both LCF and HCF testing can be used to evaluate a wide range of materials and structural components

Blue Star E&E offers state-of-the-art machines suitable for fatigue tests of metals, materials, and components under tension, compression, or reversal load. Our machines are widely used in the fields of aviation and aerospace, shipbuilding, and military industries. Get in touch with Blue Star E&E experts now to explore how our cutting-edge machines can revolutionise your testing process.