Class: BE210
Group: W2
Members:
Baker
Gilmour
Khanarian
Liu
Subhash
Date: April 2004
Abstract:
Tensile and compressive loading are not the only methods of
determining the mechanical properties of biological materials;
three-point bending tests are used to determine the flexural
properties. The flexural modulus and flexural failure strength are two
of the flexural properties that were investigated in this experiment.
The defined flexural modulus in this experiment was based upon Hooke’s
Law, σ = Ebε. The stress, σ, was defined as σ = (3PL)/(2wt2), and the
strain, ε, was defined as ε = (6yt)/L2, to give an equation for the
flexural modulus, Eb= (PL3)/(4wt3y). In these equations, P = impacting
force, L = beam length between pivots, w = beam width, t = beam
thickness, and y = displacement of the impacting wedge from starting
position. Additionally, flexural failure strength takes both
compressive and tensile strength into consideration because as the
material is flexed, one side experiences compression and the opposite,
tensile. The three-point bending jig allows a material to be impacted
on its side just as a long bone, skull, or helmet may be loaded.