Biomedical Engineering Reference
In-Depth Information
Therefore, innovative design criteria and methods for developing prophylactic
and therapeutic appliances as well as comfort related products are important.
Physical damage due to inadequate mechanical loading in the recumbent or seated
position and during walking or running (primary and/or secondary prevention) can
be avoided. In addition, pathologically altered (damaged) body regions can be
supported, so that affected anatomical structures may regain their original state and
function (tertiary prevention).
This topic is restricted to (quasi-static) biomechanical interactions between human
models and bedding and seating systems such as anti-decubitus supports, comfort
mattresses and car and aircraft seats. The main intent is to present the methodological
application of engineering science to living objects and the mechanical description of
their soft tissue properties on the basis of in vivo experiments.
The procedure itself (which we refer to as Body-Optimization and Simulation-
Systems (B OSS -Procedure)) will be described in Chap. 2 . In Chap. 3 , the necessary
medical and engineering-scientific basics of the method are provided. In Sect. 3.1 ,
magnetic resonance tomography as an essential tool, is therefore presented. In the
following Sects. 3.2 - 3.5 , engineering-scientific basics of continuum mechanics
and material theory as well as Finite Element Analysis (FEA) and numerical
parameter identification methods are introduced. Material theory is treated in
greater detail in Sect. 3.2 , since it represents the foundation for material charac-
terization of human soft tissue and support materials based on continuum
mechanical material models. In this context, the linear theory of elasticity is no
longer sufficient and knowledge of (linear-) viscoelastic material models of finite
hyperelasticity are required. Section 3.2 is not a substitute for a textbook but is
intended as an introduction to mechanics of deformable bodies. It provides a rough
overview of, among other functions, the essential strain energy functions needed to
generate stress-material equations.
In Chaps. 4 and 5 methods regarding material identification of elastic
(equilibrium elasticity at steady state) and viscoelastic properties of body support
materials and human soft tissue materials are presented. Tissue identification
includes in vivo experiments on human subjects and is presented in detail.
Section 5.3 illustrates the approach of finite element human model (B OSS -
Models) generation based on magnetic resonance imaging and 3D-reconstruction
techniques. Various human B OSS -Models are presented. These models and single
body parts reflect actual biomechanical behaviour and appearance. The human
models are approximations in the sense that, depending on the application, certain
anatomical structures such as blood vessels, ligaments, tendons or nerves are
implemented only when needed. These models can be refined and improved only
to a certain extent since medical limits (resolution of medical imaging techniques)
or computer related limits (finite element models with extensive numbers of
elements) must be observed.
Chapter 6 provides examples of body-support interactions of the B OSS -Models
generated in Chap. 5 and support systems employed in medical health care with
elastic and/or viscoelastic material properties. The necessity of judging body
support systems based on their mechanical effects on the tissue, not just at skin
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