Modeling elastic properties in finite‐element analysis: How much precision is needed to produce an accurate model?

Abstract

The influence of elastic properties on finite-element analysis was investigated using a finite-element model of a Macaca fascicularis skull. Four finite-element analyses were performed in which the model was assigned different sets of elastic properties. In analysis 1, elastic properties were modeled isotropically using published data obtained from human limb bones. Analyses 2-4 used data obtained from skulls of a closely allied species, M. mulatta, but varied as to how those data were incorporated into the model. In analysis 2, the model was assigned a single set of isotropic elastic properties. In analysis 3, each region within the model was assigned its own set of isotropic elastic properties. Finally, in analysis 4, each region received its own set of orthotropic elastic properties. Although a qualitative assessment indicates that the locations of strain concentrations across the model are broadly similar in all analyses, a quantitative assessment of strain indicates some differences between the analyses. When strain data from the finite-element analyses were compared to strain data derived from in vivo experiments, it was found that the model deformed most realistically using the orthotropic elastic properties employed in analysis 4. Results suggest that finite-element analyses can be adversely affected when elastic properties are modeled imprecisely, and that modelers should attempt to obtain elastic properties data about the species and skeletal elements that are the subjects of their analyses.

Material properties of the dentate maxilla

“…Material properties of cortical bone are also important for interpreting bone strain and for creating accurate fi- nite-element models in studies of bone deformation in response to stress (Dechow and Hylander, 2000;Richmond et al, 2005;Strait et al, 2005). Schwartz-Dabney and conclude that regions of cortical bone with greater anisotropy and greater variation in the direction of maximum stiffness result in larger errors in calculating stresses from measured bone strains, or strains from predefined loads in finite-element models.…”

Finite element analysis in functional morphology

“…In the undeformed model (a), solid arrows on the zygomatic arch illustrate the deep and superficial masseter muscle forces on working (macaque's left side) and balancing sides; dashed arrows illustrate the working-and balancing-side temporalis and medial pterygoid muscles behind the visible surface of the model. The arrows are not drawn to scale, but roughly illustrate the directions and relative magnitudes of the muscle (see Strait et al 2005, in this issue for more details). Transparent triangles show the fixed nodes on the left first molar (behind the canine) and the nodes permitting rotation but not translation at the glenoid fossa.…”

Biomechanics of phalangeal curvature

“…Although bone generally behaves anisotropically (material properties vary with orientation), data on the degree and nature (e.g., orthotropic or more complex) of anisotropy in primate phalanges are not known, nor is the variation in material properties throughout the bone (Peterson and Dechow, 2003). Furthermore, although Isotropie modeling influences strain and stress magnitudes, it appears to have little effect compared to anisotropic modeling on the pattern of stress, especially in long structures subjected to bending forces (Chen and Povirk, 1996;Strait et al, 2005). Therefore, for the comparative purposes in which FEA is used here, the phalanx was treated isotropically; that is, it was assumed that mechanical properties were equivalent in all directions.…”

“…These factors impact the biomechanical model and the resulting stress and strain distributions Ross et al, 2005;Strait et al, 2005). This study builds upon their work by constructing a biomechanical model of suspensory grasping based on measured anatomical geometry and in vivo hand posture, by validating the model against cadaver strain experiments, and by testing the effects of curvature through a carefully controlled comparison.…”