ASTM F2118 covers a test for cyclic, reverse-loading fatigue tests on acrylic bone cements. The sample is subjected up to 5,000,000 cycles of tensile and compression.
A cylindrical rod specimen is used. Samples are made from cured and hardened bone cement material. The grips can test samples with diameter between 1 to 8mm. The samples are reduced-section and are thinner in the middle than on the ends.
Universal Grip offers fatigue grips with "V" inserts to hold the rod specimens. The grip can be fashioned either from hardened tool steel or also from 303 stainless steel. The 20kN fixture is most common for ASTM F2118, however larger designs are also available.
The sample is subjected to sinusoidal tensile and compression forces for millions of cycles. The most common result is premature cracking failures. However other types of failures and alterations in the specimen can be observed by studying the data.
ASTM F2118 is commonly performed inside of a saline bath to mimic the conditions inside of the human body. The stainless steel fixture is recommended in this case.