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Biomechanical Peculiarities of Physiologically Wet Compact Bone in Cyclic Three Point Bending

By Zoja Veide, Visvaldis Vītiņš, Ivars Knēts and Modris Dobelis

Abstract

During normal activities bone is subjected to variety of combined mechanical stresses. When bone is subjected to a cyclical loading, within the bone tissue micro fractures occur which can accumulate with time. The combination of both the bone weakening effects caused by micro fractures accumulation and natural bone resorption can lead to severe stress fractures. Bending is a complex load application mode which takes place when a non-axial, offset force is applied, producing tension on one side and compression on the other. The purpose of present investigation is to describe the experimental research performed on physiologically wet bovine compact bone specimens in the cyclic three point bending test. Specimens in the form of rectangular beams (45 – 50)×(4 – 8)×(2 – 4) mm were machined from the mid-diaphysis of fresh one year old bovine femur. The first series of experiments were conducted with minimum cyclic stress level (σmin) from about 10 MPa to maximum cyclic stress level (σmax) less than 50 % of the ultimate flexural stress (σ*). The second series of experiments were carried out with σmin ≈ 0.5 σ* and σmax < σ*. The specimens were tested at room temperature 20 ± 2°C. Mechanical properties from experimental test data were calculated. The results indicate that relative cyclic strain range increases with increasing the number of loading cycles and this strain range increment has maximum in second load cycle, however relative cyclic strain range increase decreases for each consecutive load cycle. The values of mechanical properties of compact bone material depend also on the location of samples in bone cross section

Topics: Compact Bone, 3 point bending
Publisher: University of Wales College of Medicine
OAI identifier: oai:ortus.rtu.lv:3633
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