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The wing was tested for a total of 47500 flights which is 2.5 times the number of flights in 25 years of operation. Each 16 hour flight took 11 minutes to simulate on the fatigue test rig. [1] Fatigue testing is a specialised form of mechanical testing that is performed by applying cyclic loading to a coupon or structure.
However, extensive testing would have been too costly so researchers mainly resorted to using finite element analysis using computer software. [2] A graph comparing the number of cycles to failure for low cycle fatigue and high cycle fatigue. Through many experiments, it has been found that characteristics of a material can change as a result ...
It is usually performed using a standard fatigue testing machine where the test specimen is prepared in a specifically defined manner and then subjected to loads until failure takes place. Throughout the test, computer software is used to record various necessary parameters such as the number of cycles experienced and the exact point of failure.
Some materials (e.g., some steel and titanium alloys) exhibit a theoretical fatigue limit below which continued loading does not lead to fatigue failure. High cycle fatigue strength (about 10 4 to 10 8 cycles) can be described by stress-based parameters. A load-controlled servo-hydraulic test rig is commonly used in these tests, with ...
Fatigue tests on coupons are typically conducted using servo hydraulic test machines which are capable of applying large variable amplitude cyclic loads. [4] Constant amplitude testing can also be applied by simpler oscillating machines. The fatigue life of a coupon is the number of cycles it takes to break the coupon. This data can be used for ...
Compact tension specimens are used extensively in the area of fracture mechanics and corrosion testing, in order to establish fracture toughness and fatigue crack growth data for a material. The purpose of using a notched sample is to create a fatigue crack by applying cyclic loading through pins inserted into the holes on the sample using a ...
Rainflow counting identifies the closed cycles in a stress-strain curve. The rainflow-counting algorithm is used in calculating the fatigue life of a component in order to convert a loading sequence of varying stress into a set of constant amplitude stress reversals with equivalent fatigue damage.
It is the result of the process of fatigue due to rolling/sliding contact. [2] [3] The RCF process begins with cyclic loading of the material, which results in fatigue damage that can be observed in crack-like flaws, like white etching cracks. [2] These flaws can grow into larger cracks under further loading, potentially leading to fractures ...