Mechanical hysteresis loops from single osteons: Technical devices and preliminary results

Orientation of collagen at the osteocyte lacunae in human secondary osteons

“…The angle between the elementary components' orientation and the loading direction was observed to affect strain and stress fields. The proposed ''lacuna-enhanced osteon'' model displays the axial deformation observed experimentally Bonucci, 1967, 1968;Ascenzi et al, 1985Ascenzi et al, , 1997. The mesh density was established through a convergence study on an increasing number of nodes, from 58,100 to 1,917,873.…”

“…The morphometric data were included in a series of finite element models that simulated the mechanical behavior of single secondary osteon Bonucci, 1967, 1968;Ascenzi et al, 1985Ascenzi et al, , 1997 with lacunae. To probe the role of collagen-apatite orientation, the alternative option was included to assign constant homogeneous material properties to all the elements of the model.…”

Hysteretic pinching of human secondary osteons subjected to torsion

“…Because the presence of the bright lamellae in osteons affects in opposite ways the stiffness under tension and under compression Bonucci, 1967, 1968), cyclic loading under tension-compression (Ascenzi et al, 1985(Ascenzi et al, , 1997 showed an asymmetry due to the relative beginning of the half-cycle. Such asymmetry does not appear ( Fig.…”

“…However, cycling loops that appear ''pinched'' or S-shaped, as opposed to C-shaped ( Fig. 1 depicts idealized shapes) have been observed for single osteons under tension-compression loading (Ascenzi et al, 1985). Extensive research on torsional behavior of bone (for a review, see Ascenzi et al, 1994) has linked such behavior to tissue properties, as predicted by Rauber (Rauber, 1876).…”

“…From the preselected region, a micro-mill and a micro-lathe (Ascenzi et al, 1985) were employed to cut a specimen consisting of a cylindrical central portion, coaxial with the embedded Haversian canal, extending into two lugs (Fig. 3).…”