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

1. ABSTRACT
PASSIVE AND ACTIVE MUSCLE TISSUE APPROACH
FOR HUMAN BODY MODEL CASIMIR
A. Siefert 1 and T. Siebert 2
Detailed human body models are applied in a wide range of scientific and industrial
investigations. Thereby, the focus nowadays is more and more shifted to the evaluation
or inclusion of internal model states, as e.g. detailed stresses and strains of the tissue,
leading to enhanced applications within the medical or automotive sector.
Meeting this challenge the human body model CASIMIR 1 is continuously improved.
One aspect in this process is the generation of a detailed geometric model setup based
on MRI data enabling investigations with a higher resolution. Besides the focus is on
the adequate representation of the mechanical properties of the soft tissues. Thereby the
modeling of the skeletal muscles causes particular requirements as the active
filamentary force transmission has to be coupled with the passive volumetric behavior.
The work here presented describes the latest development, including an enhanced
approach for the coupling of active and passive behavior within an isolated muscle. The
validation by comparison with measurements consists of a three dimensional load case.
Furthermore, as a first step the invented modeling method is implemented within a
detailed buttock model of CASIMIR. Using this approach for the simulation of a typical
driving scenario, i.e. activation of knee flexors required for pedal operations, the real
behavior out of test person measurements could be shown.
2. INTRODUCTION
The application of human body models is continuously increasing as improved
numerical simulation capabilities enable detailed simulations with acceptable effort. The
human body model CASIMIR was invented in the 1990s with the initial goal to
compute internal forces acting on the lumbar spine due to vibrational exposure. Within
the last 15 years the model has been improved stepwise (see Fig. 1) and nowadays is
used to investigate static and dynamic seating comfort 1 .
(a) (b) (c)
Fig. 1: CASIMIR current model (a) and detailed approach for buttocks (b, c)
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1 Assistant Manager, Seating Comfort and Biomechanics, Woelfel Beratende Ingenieure GmbH + Co.KG,
97204 Hoechberg, Germany
2 Scientific Researcher, Department of Motion Science, Friedrich-Schiller-University, 07749 Jena,
Germany