Fatigue Failure

Description

Mr Shiraz Sabah gives his expert insights and explains the concept of fatigue failure in materials, highlighting how they can break under repeated cyclical loading even if the force is below the level that would cause one-time failure. The ultimate tensile stress is defined, and a classroom analogy using a plastic ruler illustrates how repeated bending leads to tiny cracks and eventual breakage. Mr Sabah also contrasts materials with endurance limits, like steel, which can withstand infinite cycles below a certain stress, against those like plastics and titanium alloys that weaken over time without a true endurance limit. The application of this knowledge in orthopaedics is emphasized, particularly in relation to cemented femoral stems, which can fail after 7 to 10 years, especially in larger patients.

DOI: 10.1302/3114-251244