ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

Figure 1. Range of parameter CCE for active stress calculation
Alternative CCE values were explored by keeping the relative activations of the muscles
modelled as suggested by the relation of ζCE to the functional geometrical characteristics
of these muscles (Table 3).
Table 3. Alternative CCE values suggested for lumbar muscles
compression traction
MF 0.706 0.465
LT 0.718 0.473
IL 0.737 0.485
PS 0.967 0.637
For all muscles tested, the new stress results obtained (Fig. 2a) were within the plausible
range of values reported in literature [10] for values between 0.9 and 1.1. The
relative contribution of the different terms in the total stress indicated the dominant role
of the active fibre term followed by the passive volumetric term for MF, LT and IL
muscles for traction up to = 1.2 (Fig. 2b). For PS, on the contrary, the passive
volumetric resistance had the highest contribution in the total stress.
Figure 2. (a) Normal Cauchy stress for MF, LT, IL & PS muscles, (b) Relative contributions of stress
terms for =1.2
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